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FeGaB_-_abstract.csv

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+publicationDate,title,abstract,id
+2022-01-12,Light and microwave driven spin pumping across FeGaB-BiSb interface,"3-D topological insulators (TI) with large spin Hall conductivity have
+emerged as potential candidates for spintronic applications. Here, we report
+spin to charge conversion in bilayers of amorphous ferromagnet (FM)
+Fe_{78}Ga_{13}B_{9} (FeGaB) and 3-D TI Bi_{85}Sb_{15} (BiSb) activated by two
+complementary techniques: spin pumping and ultrafast spin-current injection. DC
+magnetization measurements establish the soft magnetic character of FeGaB
+films, which remains unaltered in the heterostructures of FeGaB-BiSb. Broadband
+ferromagnetic resonance (FMR) studies reveal enhanced damping of precessing
+magnetization and large value of spin mixing conductance (5.03 x 10^{19}
+m^{-2}) as the spin angular momentum leaks into the TI layer. Magnetic field
+controlled bipolar dc voltage generated across the TI layer by inverse spin
+Hall effect is analyzed to extract the values of spin Hall angle and spin
+diffusion length of BiSb. The spin pumping parameters derived from the
+measurements of the femtosecond light-pulse-induced terahertz emission are
+consistent with the result of FMR. Kubo-Bastin formula and tight-binding model
+calculations shed light on the thickness-dependent spin-Hall conductivity of
+the TI films, with predictions that are in remarkable agreement with the
+experimental data. Our results suggest that room temperature deposited
+amorphous and polycrystalline heterostructures provide a promising platform for
+creating novel spin orbit torque devices.",2201.04686v1
+2024-03-21,Picotesla-sensitivity microcavity optomechanical magnetometry,"Cavity optomechanical systems have enabled precision sensing of magnetic
+fields, by leveraging the optical resonance-enhanced readout and mechanical
+resonance-enhanced response. Previous studies have successfully achieved
+scalable and reproducible microcavity optomechanical magnetometry (MCOM) by
+incorporating Terfenol-D thin films into high-quality ($Q$) factor whispering
+gallery mode (WGM) microcavities. However, the sensitivity was limited to 585
+pT/Hz$^{1/2}$, over 20 times inferior to those using Terfenol-D particles. In
+this work, we propose and demonstrate a high-sensitivity and scalable MCOM
+approach by sputtering a FeGaB thin film onto a high-$Q$ SiO$_2$ WGM microdisk.
+Theoretical studies are conducted to explore the magnetic actuation constant
+and noise-limited sensitivity by varying the parameters of the FeGaB film and
+SiO$_2$ microdisk. Multiple magnetometers with different radii are fabricated
+and characterized. By utilizing a microdisk with a radius of 355 $\mu$m and a
+thickness of 1 $\mu$m, along with a FeGaB film with a radius of 330 $\mu$m and
+a thickness of 1.3 $\mu$m, we have achieved a remarkable peak sensitivity of
+1.68 pT/Hz$^{1/2}$ at 9.52 MHz. This represents a significant improvement of
+over two orders of magnitude compared with previous studies employing sputtered
+Terfenol-D film. Notably, the magnetometer operates without a bias magnetic
+field, thanks to the remarkable soft magnetic properties of the FeGaB film.
+Furthermore, as a proof-of-concept, we have demonstrated the real-time
+measurement of a pulsed magnetic field simulating the corona current in a
+high-voltage transmission line using our developed magnetometer. These
+high-sensitivity magnetometers hold great potential for various applications,
+such as magnetic induction tomography and corona current monitoring.",2403.14301v1
+2015-08-28,Control of magnetic relaxation by electric-field-induced ferroelectric phase transition and inhomogeneous domain switching,"Electric-field modulation of magnetism in strain-mediated multiferroic
+heterostructures is considered a promising scheme for enabling memory and
+magnetic microwave devices with ultralow power consumption. However, it is not
+well understood how electric-field-induced strain influences magnetic
+relaxation, an important physical process for device applications. Here we
+investigate resonant magnetization dynamics in ferromagnet/ferrolectric
+multiferroic heterostructures, FeGaB/PMN-PT and NiFe/PMN-PT, in two distinct
+strain states provided by electric-field-induced ferroelectric phase
+transition. The strain not only modifies magnetic anisotropy but also magnetic
+relaxation. In FeGaB/PMN-PT, we observe a nearly two-fold change in intrinsic
+Gilbert damping by electric field, which is attributed to strain-induced tuning
+of spin-orbit coupling. By contrast, a small but measurable change in extrinsic
+linewidth broadening is attributed to inhomogeneous ferroelastic domain
+switching during the phase transition of the PMN-PT substrate.",1508.07290v2
+2022-01-11,Resonant Precession of Magnetization and Precession -- Induced DC voltages in FeGaB Thin Films,"Measurements of frequency dependent ferromagnetic resonance (FMR) and spin
+pumping driven dc voltage (V_{dc}) are reported for amorphous films of
+Fe_{78}Ga_{13}B_{9} (FeGaB) alloy to address the phenomenon of self-induced
+inverse spin Hall effect (ISHE) in plain films of metallic ferromagnets. The
+V_{dc} signal, which is antisymmetric on field reversal, comprises of symmetric
+and asymmetric Lorentzians centered around the resonance field. Dominant role
+of thin film size effects is seen in setting the magnitude of static
+magnetization, V_{dc} and dynamics of magnetization precession in thinner films
+(\leq 8 nm). The film thickness dependence of magnetization parameters
+indicates the presence of a magnetically disordered region at the
+film-substrate interface, which may promote preferential flow of spins
+generated by the precessing magnetization towards the substrate. However, the
+V_{dc} signal also draws contributions from rectification effects of a \approx
+0.4 \% anisotropic magnetoresistance and a large (\approx 54 n\Omega.m)
+anomalous Hall resistivity (AHR) of these films which ride over the effect of
+spin-orbit coupling driven spin-to-charge conversion near the film-substrate
+interface. We have addressed these data in the framework of the existing
+theories of electrodynamics of a ferromagnetic film subjected to
+radio-frequency field in a coplanar waveguide geometry. Our estimation of the
+self-induced ISHE for the sample with 54 n\Omega.m AHR shows that it may
+contribute significantly (\approx 90\%) to the measured symmetric voltage. This
+study is expected to be very useful for fully understanding the spin pumping
+induced dc voltages in metallic ferromagnets with disordered interfaces and
+large anomalous Hall effect.",2201.03739v1
+2014-11-22,Quantification of the spin-Hall anti-damping torque with a resonance spectrometer,"We present a simple technique using a cavity-based resonance spectrometer to
+quantify the anti-damping torque due to the spin Hall effect. Modification of
+ferromagnetic resonance is observed as a function of small DC current in
+sub-mm-wide strips of bilayers, consisting of magnetically soft FeGaB and
+strong spin-Hall metal Ta. From the detected current-induced linewidth change,
+we obtain an effective spin Hall angle of 0.08-0.09 independent of the magnetic
+layer thickness. Our results demonstrate that a sensitive resonance
+spectrometer can be a general tool to investigate spin Hall effects in various
+material systems, even those with vanishingly low conductivity and
+magnetoresistance.",1411.6166v1
+2021-12-10,Enhanced Planar Antenna Efficiency Through Magnetic Thin-Films,"This work proposes to use magnetic material as the substrate of planar
+antennas to overcome the platform effect caused by the conducting ground plane.
+The upper bound of the radiation efficiency of an electric-current-driven
+low-profile antenna is theoretically derived, which is inversely proportional
+to the Gilbert damping factor of the magnetic material. Meanwhile, the
+improvement of radiation due to the use of magnetic material is demonstrated by
+a three-dimensional (3D) multiphysics and multiscale time-domain model. The
+simulation results match the theoretical derivation, showing 25% radiation
+efficiency from a planar antenna backed by a FeGaB thin film with 2.56 um
+thickness. Furthermore, for conductive ferromagnetic materials, it is shown
+that the eddy current loss can be well suppressed by laminating the thin film
+into multiple layers. The radiation efficiency of the modeled antenna with a
+conductive ferromagnetic substrate is improved from 2.2% to 11.8% by dividing
+the substrate into 10 layers, with a ferromagnetic material fill factor of 93%.",2201.04932v1

half-metal_-_abstract.csv

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+publicationDate,title,abstract,id
+2023-04-08,Genuine Dirac half-metal: A 2D d0-type ferromagnet Mg4N4,"When the spin-orbit coupling (SOC) is absent, almost all the proposed
+half-metals with the twofold degenerate nodal points at the K (or K') in
+two-dimensional (2D) materials are misclassified as ""Dirac half-metals"" owing
+to the way graphene was utilized in the earliest studies. Actually, each band
+crossing point at K or K' is described by a 2D Weyl Hamiltonian with definite
+chirality; hence, it must be a Weyl point. To the best of our knowledge, there
+have been no reports of a genuine (i.e., fourfold degenerate) Dirac point
+half-metal in 2D yet. In this Letter, we proposed for the first time that the
+2D d0-type ferromagnet Mg4N4 is a genuine Dirac half-metal with a fourfold
+degenerate Dirac point at the S high-symmetry point, intrinsic magnetism, high
+Curie temperature, 100% spin-polarization, robustness to the SOC and uniaxial
+and biaxial strains, and 100% spin-polarized edge states. The work can be seen
+as a starting point for future predictions of intrinsically magnetic materials
+with genuine Dirac points, which will aid the frontier of topo-spintronics
+researchers.",2304.03919v1