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2008-04-26 | Origin of resistivity minima at low temperature in ferromagnetic metallic manganites | The resistivity and magnetoresistance measurements were carried out on thin
film of La0.7Ca0.3MnO3 to investigate the possible origin of low temperature
resistivity minimum observed in these samples. We observed large hysteresis in
the magnetoresistance at low temperature; 5K and the sample current I has large
effect on resistivity minima temperature. The observation of hysteresis at low
temperatures suggests the presence of inhomogeneity at low temperatures. These
in-homogeneities consist of regions of different resistive phases. It appears
that the high resistive phase prevents the tunneling of charge carriers between
two low resistive regions and thus giving rise to the resistivity minimum in
these samples. | 0804.4247v1 |
2015-08-05 | The universal influence of contact resistance on the efficiency of a thermoelectric generator | The influence of electrical and thermal contact resistance on the efficiency
of a segmented thermoelectric generator is investigated. We consider 12
different segmented $p$-legs and 12 different segmented $n$-legs, using 8
different $p$-type and 8 different $n$-type thermoelectric materials. For all
systems a universal influence of both the electrical and thermal contact
resistance is observed on the leg's efficiency, when the systems are analyzed
in terms of the contribution of the contact resistance to the total resistance
of the leg. The results are compared with the analytical model of Min and Rowe
(1992). In order for the efficiency not to decrease more than 20%, the contact
electrical resistance should be less than 30% of the total leg resistance for
zero thermal contact resistance, while the thermal contact resistance should be
less than 20% for zero electrical contact resistance. The universal behavior
also allowed the maximum tolerable contact resistance for a segmented system to
be found, i.e. the resistance at which a leg of only the high temperature
thermoelectric material has the same efficiency as the segmented leg with a
contact resistance at the interface. If e.g. segmentation increases the
efficiency by 30% then an electrical contact resistance of 30% or a thermal
contact resistance of 20% can be tolerated. | 1508.01153v1 |
2018-02-10 | Electroforming Free Controlled Bipolar Resistive Switching in Al/CoFe2O4/FTO device with Self-Compliance Effect | Controlled bipolar resistive switching (BRS) has been observed in
nanostructured CoFe2O4 films using Al(aluminum)/CoFe2O4/FTO(fluorine-doped tin
oxide) device. The fabricated device shows electroforming-free uniform BRS with
two clearly distinguished and stable resistance states without any application
of compliance current (CC), with a resistance ratio of high resistance state
(HRS) and low resistance state (LRS) > 102. Small switching voltage (< 1 volt)
and lower current in both the resistance states confirms the fabrication of low
power consumption device. In the LRS, the conduction mechanism was found to be
of Ohmic in nature, while the high-resistance state (HRS/OFF state) was
governed by space charge-limited conduction mechanism, which indicates the
presence of an interfacial layer with imperfect microstructure near the top
Al/CFO interface. The device shows nonvolatile behavior with good endurance
properties, acceptable resistance ratio, uniform resistive switching due to
stable, less random filament formation/rupture and a control over the resistive
switching properties by choosing different stop voltages, which makes the
device suitable for its application in future nonvolatile resistive random
access memory (ReRAM). | 1802.03643v1 |
2021-08-20 | Understanding grain boundary electrical resistivity in Cu: the effect of boundary structure | Grain boundaries (GBs) in metals usually increase electrical resistivity due
to their distinct atomic arrangement compared to the grain interior. While the
GB structure has a crucial influence on the electrical properties, its
relationship with resistivity is poorly understood. Here, we perform a
systematic study on the resistivity and structure relationship in Cu tilt GBs,
employing high resolution in-situ electrical measurements coupled with atomic
structure analysis of the GBs. Excess volume and energies of selected GBs are
calculated using molecular dynamics simulations. We find a consistent relation
between the coincidence site lattice (CSL) type of the GB and its resistivity.
The most resistive GBs are high range of low-angle GBs (misorientation 14 to 18
degrees) with twice the resistivity of high angle tilt GBs, due to the high
dislocation density and corresponding strain fields. Regarding the atomistic
structure, GB resistivity approximately correlates with the GB excess volume.
Moreover, we show that GB curvature increases resistivity by about 80%, while
phase variations and defects within the same CSL type do not considerably
change it. | 2108.09148v1 |
2003-12-07 | Temperature-dependent contact resistances in high-quality polymer field-effect transistors | Contact resistances between organic semiconductors and metals can dominate
the transport properties of electronic devices incorporating such materials. We
report measurements of the parasitic contact resistance and the true channel
resistance in bottom contact poly(3-hexylthiophene) (P3HT) field-effect
transistors with channel lengths from 400 nm up to 40 $\mu$m, from room
temperature down to 77 K. For fixed gate voltage, the ratio of contact to
channel resistance decreases with decreasing temperature. We compare this
result with a recent model for metal-organic semiconductor contacts. Mobilities
corrected for this contact resistance can approach 1 cm$^{2}$/Vs at room
temperature and high gate voltages. | 0312183v1 |
2024-02-26 | A novel method for determining the resistivity of compressed superconducting materials | The resistivity of a superconductor in its normal state plays a critical role
in determining its superconducting ground state. However, measuring the
resistivity of a material under high pressure has long presented a significant
technical challenge due to pressure-induced changes in the crystallographic
directions, especially for samples with anisotropic layered structures like
high-Tc superconductors and other intriguing quantum materials. Here, we are
the first to propose a novel and effective method for determining high-pressure
resistivity, which relies on the ambient-pressure resistivity, initial sample
sizes, lattice parameters, high-pressure resistance, and lattice parameters
measured from the same sample. Its validity has been confirmed through our
investigations of pressurized copper-oxide superconductors, which demonstrates
that this method provides new possibilities for researchers conducting
high-pressure studies related to resistivity of these materials. | 2402.16257v1 |
2021-09-14 | Internal reverse-biased p-n junctions: a possible origin of the high resistance in phase change superlattice | Phase change superlattice is one of the emerging material technologies for
ultralow-power phase change memories. However, the resistance switching
mechanism of phase change superlattice is still hotly debated. Early electrical
measurements and recent materials characterizations have suggested that the
Kooi phase is very likely to be the as-fabricated low-resistance state. Due to
the difficulty in in-situ characterization at atomic resolution, the structure
of the electrically switched superlattice in its high-resistance state is still
unknown and mainly investigated by theoretical modellings. So far, there has
been no simple model that can unify experimental results obtained from
device-level electrical measurements and atomic-level materials
characterizations. In this work, we carry out atomistic transport modellings of
the phase change superlattice device and propose a simple mechanism accounting
for its high resistance. The modeled high-resistance state is based on the
interfacial phase changed superlattice that has previously been mistaken for
the low-resistance state. This work advances the understanding of phase change
superlattice for emerging memory applications. | 2109.06376v1 |
2018-04-23 | Magnetic field-induced resistivity upturn and exceptional magneto-resistance in Weyl semimetal TaSb2 | We study magneto-transport properties in single crystals of TaSb_2, which is
a recently discovered topological semimetal. In the presence of magnetic field,
the electrical resistivity shows onset of insulating behaviour followed by
plateau at low temperature. Such resistivity plateau is generally assigned to
topological surface states. TaSb2 exhibits extremely high magneto-resistance
with non-saturating field dependence. We find that aspects of extremely large
magneto resistance and resistivity plateau are well accounted by classical
Kohler scaling. Unambiguous evidence for anomalous Chiral transport is provided
with observation of negative longitudinal magneto-resistance. Shubnikov-de Haas
oscillations reveal two dominating frequencies, 201 T and 455 T. These aspects
categorize TaSb2 as a Type-II Weyl semimetal. At low temperature, the field
dependence of Hall resistivity shows non-linear behaviour that indicates the
presence of two types of charge carriers in consonance with reported electronic
band structure. Analysis of Hall resistivity imply very high electron
mobilities. | 1804.08434v1 |
2023-07-12 | Machine learning accelerated discovery of corrosion-resistant high-entropy alloys | Corrosion has a wide impact on society, causing catastrophic damage to
structurally engineered components. An emerging class of corrosion-resistant
materials are high-entropy alloys. However, high-entropy alloys live in
high-dimensional composition and configuration space, making materials designs
via experimental trial-and-error or brute-force ab initio calculations almost
impossible. Here we develop a physics-informed machine-learning framework to
identify corrosion-resistant high-entropy alloys. Three metrics are used to
evaluate the corrosion resistance, including single-phase formability, surface
energy and Pilling-Bedworth ratios. We used random forest models to predict the
single-phase formability, trained on an experimental dataset. Machine learning
inter-atomic potentials were employed to calculate surface energies and
Pilling-Bedworth ratios, which are trained on first-principles data fast
sampled using embedded atom models. A combination of random forest models and
high-fidelity machine learning potentials represents the first of its kind to
relate chemical compositions to corrosion resistance of high-entropy alloys,
paving the way for automatic design of materials with superior corrosion
protection. This framework was demonstrated on AlCrFeCoNi high-entropy alloys
and we identified composition regions with high corrosion resistance. Machine
learning predicted lattice constants and surface energies are consistent with
values by first-principles calculations. The predicted single-phase formability
and corrosion-resistant compositions of AlCrFeCoNi agree well with experiments.
This framework is general in its application and applicable to other materials,
enabling high-throughput screening of material candidates and potentially
reducing the turnaround time for integrated computational materials
engineering. | 2307.06384v3 |
2014-08-26 | Enhancement in Quality Factor of SRF Niobium Cavities by Material Diffusion | An increase in the quality factor of superconducting radiofrequency cavities
is achieved by minimizing the surface resistance during processing steps. The
surface resistance is the sum of temperature independent residual resistance
and temperature/material dependent Bardeen-Cooper-Schrieffer (BCS) resistance.
High temperature heat treatment usually reduces the impurities concentration
from the bulk niobium, lowering the residual resistance. The BCS part can be
reduced by selectively doping non-magnetic impurities. The increase in quality
factor, termed as Q-rise, was observed in cavities when titanium or nitrogen
thermally diffused in the inner cavity surface. | 1408.6245v1 |
2015-12-15 | A Graphene-Carbon Nanotube Hybrid Material for Photovoltaic Applications | Large area graphene sheets grown by chemical vapor deposition can potentially
be employed as a transparent electrode in photovoltaics if their sheet
resistance can be significantly lowered, without any loss in transparency.
Here, we report the fabrication of a graphene-conducting-carbon-nanotube (CCNT)
hybrid material with a sheet resistance considerably lower than neat graphene,
and with the requisite small reduction in transparency. Graphene is deposited
on top of a a self-assembled CCNT monolayer which creates parallel conducting
paths on the graphene surface. The hybrid thereby circumvents electron
scattering due to defects in the graphene sheet, and reduces the sheet
resistance by a factor of two. The resistance can be further reduced by
chemically doping the hybrid. Moreover, the chemically doped hybrid is more
stable than a standalone chemically doped graphene sheet, as the CCNT network
enhances the dopant binding. In order to understand the results, we develop a
2D resistance network model in which we couple the CCNT layer to the graphene
sheet and demonstrate the model accounts quantitatively for the resistance
decrease. Our results show that a graphene-CCNT hybrid system has high
potential for use as a transparent electrode with high transparency and low
sheet resistance. | 1512.04617v1 |
2022-06-11 | Modeling of High and Low Resistant States in Single Defect Atomristors | Resistance-change random access memory (RRAM) devices are nanoscale
metal-insulator-metal structures that can store information in their resistance
states, namely the high resistance (HRS) and low resistance (LRS) states. They
are a potential candidate for a universal memory as these non-volatile memory
elements can offer fast-switching, long retention and switching cycles, and
additionally, are also suitable for direct applications in neuromorphic
computing. In this study, we first present a model to analyze different
resistance states of RRAM devices or so-called "atomristors" that utilize novel
2D materials as the switching materials instead of insulators. The developed
model is then used to study the electrical characteristics of a single defect
monolayer MoS$_{2}$ memristor. The change in the device resistance between the
HRS and LRS is associated to the change in the tunneling probability when the
vacancy defects in the 2D material are substituted by the metal atoms from the
electrodes. The distortion due to defects and substituted metal atom is
captured in the 1D potential energy profile by averaging the effect along the
transverse direction. This simplification enables us to model single defect
memristors with a less extensive quantum transport model while taking into
account the presence of defects. | 2206.05504v1 |
2011-06-06 | Efficient resistive memory effect on SrTiO3 by ionic-bombardment | SrTiO3 is known to exhibit resistive memory effect either with cation-doping
or with high-temperature thermal reduction. Here, we add another scheme,
ionic-bombardment, to the list of tools to create resistive memory effect on
SrTiO3 (STO). In an Ar-bombarded STO crystal, two orders of resistance
difference was observed between the high and low resistive states, which is an
order of magnitude larger than those achieved by the conventional thermal
reduction process. One of the advantages of this new scheme is that it can be
easily combined with lithographic processes to create spatially-selective
memory effect. | 1106.1203v1 |
2006-02-21 | Evidance for an Oxygen Diffusion Model for the Electric Pulse Induced Resistance Change Effect in Oxides | Electric pulse induced resistance (EPIR) switching hysteresis loops for
Pr0.7Ca0.7MnO3 (PCMO) perovskite oxide films were found to exhibit an
additional sharp "shuttle peak" around the negative pulse maximum for films
deposited in an oxygen deficient ambient. The device resistance hysteresis loop
consists of stable high resistance and low resistance states, and transition
regions between them. The resistance relaxation of the "shuttle peak" and its
temperature behavior as well as the resistance relaxation in the transition
regions were studied, and indicate that the resistance switching relates to
oxygen diffusion with activation energy about 0.4eV. An oxygen diffusion model
with the oxygen ions (vacancies) as the active agent is proposed for the
non-volatile resistance switching effect in PCMO. | 0602507v2 |
2014-06-16 | Degenerate Resistive Switching and Ultrahigh Density Storage in Resistive Memory | We show that, in tantalum oxide resistive memories, activation power provides
a multi-level variable for information storage that can be set and read
separately from the resistance. These two state variables (resistance and
activation power) can be precisely controlled in two steps: (1) the possible
activation power states are selected by partially reducing resistance, then (2)
a subsequent partial increase in resistance specifies the resistance state and
the final activation power state. We show that these states can be precisely
written and read electrically, making this approach potentially amenable for
ultra-high density memories. We provide a theoretical explanation for
information storage and retrieval from activation power and experimentally
demonstrate information storage in a third dimension related to the change in
activation power with resistance. | 1406.4033v1 |
2020-06-10 | Positive versus negative resistance response to hydrogenation in palladium and its alloys | Resistive solid state sensors are widely used in multiple applications,
including molecular and gas detection. Absorption or intercalation of the
target species varies the lattice parameters and an effective thickness of thin
films, which is usually neglected in analyzing their transport properties in
general and the sensor response in particular. Here, we explore the case of
palladium-based thin films absorbing hydrogen and demonstrate that expansion of
thickness is an important mechanism determining the magnitude and the very
polarity of the resistance response to hydrogenation in high resistivity films.
The model of the resistance response that takes into account modifications of
thickness was tested and confirmed in three Pd-based systems with variable
resistivity: thin Pd films above and below the percolation threshold, thick
Pd-SiO2 granular composite films with different content of silica, and Pd-rich
CoPd alloys where resistivity depends on Co concentration. Superposition of the
bulk resistivity increase due to hydride formation and decrease of film
resistance due to thickness expansion provides a consistent explanation of the
hydrogenation response in both continuous and discontinuous films with
different structures and compositions. | 2006.05801v1 |
2021-06-04 | Noncured Graphene Thermal Interface Materials: Minimizing the Thermal Contact Resistance | We report on experimental investigation of thermal contact resistance of the
noncuring graphene thermal interface materials with the surfaces characterized
by different degree of roughness. It is found that the thermal contact
resistance depends on the graphene loading non-monotonically, achieving its
minimum at the loading fraction of ~15 wt.%. Increasing the surface roughness
by ~1 micrometer results in approximately the factor of x2 increase in the
thermal contact resistance for this graphene loading. The obtained dependences
of the thermal conductivity, thermal contact resistance, and the total thermal
resistance of the thermal interface material layer on the graphene loading and
surface roughness indicate the need for optimization of the loading fraction
for specific materials and roughness of the connecting surfaces. Our results
are important for developing graphene technologies for thermal management of
high-power-density electronics. | 2106.02180v1 |
2002-10-24 | Violation of Ioffe-Regel condition but saturation of resistivity of the high Tc cuprates | We demonstrate that the resistivity data of a number of high Tc cuprates, in
particular La(2-x)SrxCuO4, are consistent with resistivity saturation, although
the Ioffe-Regel condition is strongly violated. By using the f-sum rule
together with calculations of the kinetic energy in the t-J model, we show that
the saturation resistivity is unusually large. This is related to the strong
reduction of the kinetic energy due to strong correlation effects. The
fulfilment of the Ioffe-Regel condition for conventional transition metal
compounds is found to be somewhat accidental. | 0210543v1 |
2023-04-26 | Theoretical Puncture Mechanics of Soft Compressible Solids | Accurate prediction of the force required to puncture a soft material is
critical in many fields like medical technology, food processing, and
manufacturing. However, such a prediction strongly depends on our understanding
of the complex nonlinear behavior of the material subject to deep indentation
and complex failure mechanisms. Only recently we developed theories capable of
correlating puncture force with material properties and needle geometry.
However, such models are based on simplifications that seldom limit their
applicability to real cases. One common assumption is the incompressibility of
the cut material, albeit no material is truly incompressible. In this paper we
propose a simple model that accounts for linearly elastic compressibility, and
its interplay with toughness, stiffness, and elastic strain-stiffening.
Confirming previous theories and experiments, materials having high-toughness
and low-modulus exhibit the highest puncture resistance at a given needle
radius. Surprisingly, in these conditions, we observe that incompressible
materials exhibit the lowest puncture resistance, where volumetric
compressibility can create an additional (strain) energy barrier to puncture.
Our model provides a valuable tool to assess the puncture resistance of soft
compressible materials and suggests new design strategies for sharp needles and
puncture-resistant materials. | 2304.13838v1 |
2008-05-23 | Non-hysteretic branches inside the hysteresis loop in VO2 films for focal plane array imaging bolometers | In the resistive phase transition in VO2, temperature excursions from points
on the major hysteresis loop produce minor loops. We have found that for
sufficiently small excursions these minor loops degenerate into single-valued,
non-hysteretic branches (NHBs) having essentially the same or even higher
temperature coefficient of resistance (TCR) as the semiconducting phase at room
temperature. We explain this behavior and discuss the opportunities it presents
for infrared imaging technology based on resistive microbolometers. It is
possible to choose a NHB with 100 to 1000 times smaller resistivity than in a
pure semiconducting phase, thus providing a microbolometer with low tunable
resistivity and high TCR. | 0805.3566v1 |
2021-05-26 | Investigation of Forming Free Bipolar Resistive Switching Characteristics in Al/Mn3O4/FTO RRAM Device | Bipolar resistive switching (BRS) phenomenon has been demonstrated in Mn3O4
using Al (Aluminum)/Mn3O4/FTO (Fluorine doped Tin Oxide) Resistive Random
Access Memory (RRAM) device. The fabricated RRAM device shows good retention,
non volatile behavior and forming free BRS. The Current-Voltage (I-V)
characteristics and the temperature dependence of the resistance (R-T)
measurements were used to explore conduction mechanisms and the thermal
activation energy (Ea). The resistance ratio of high resistance state (HRS) to
low resistance state (LRS) is ~102. The fabricated RRAM device shows different
conduction mechanisms in LRS and HRS state such as ohmic conduction and space
charge limited conduction (SCLC). The rupture and formation of conducting
filaments (CF) of oxygen vacancies take place by changing the polarity of
external voltage, which may be responsible for resistive switching
characteristics in the fabricated RRAM device. This fabricated RRAM device is
suitable for application in future high density non-volatile memory (NVM) RRAM
devices. | 2105.12390v1 |
1998-08-18 | Resistivity saturation revisited: results from a dynamical mean field theory | We use the dynamical mean field method to study the high-temperature
resistivity of electrons strongly coupled to phonons. The results reproduce the
qualtiative behavior of the temperature and disorder dependence of the
resistivity of the 'A-15' materials, which is commonly described in terms of
saturation, but imply that the resistivity does not saturate. Rather, a change
in temperature dependence occurs when the scattering becomes strong enough to
cause a breakdown of the Migdal approximation. | 9808188v2 |
2018-07-13 | A new type of RPC with very low resistive material | There are several working groups that are currently working on high rate
RPC's using different materials such as Si-based Ceramics, Low-resistive Glass,
low-resistive bakelite etc. A new type of single gap RPC has been fabricated
using very low-resistive carbon-loaded PTFE material to compete with all these
other groups and materials. In terms of bulk resistivity, this material is the
lowest and should in principle be able to work at the highest rates, provided
the material can withstand working bias and radiation. The efficiency and noise
rate of the RPC are measured with cosmic rays. The detail method of fabrication
and first experimental results are presented. | 1807.04984v1 |
2013-04-20 | Electric-Field-Induced Resistive Switching in a Family of Mott Insulators : towards Non-Volatile Mott-RRAM Memories | The fundamental building blocks of modern silicon-based microelectronics,
such as double gate transistors in non-volatile Flash memories, are based on
the control of electrical resistance by electrostatic charging. Flash memories
could soon reach their miniaturization limits mostly because reliably keeping
enough electrons in an always smaller cell size will become increasingly
difficult . The control of electrical resistance at the nanometer scale
therefore requires new concepts, and the ultimate resistance-change device is
believed to exploit a purely electronic phase change such as the Mott insulator
to insulator transition [2]. Here we show that application of short electric
pulses allows to switch back and forth between an initial high-resistance
insulating state ("0" state) and a low-resistance "metallic" state ("1" state)
in the whole class of Mott Insulator compounds AM4X8 (A = Ga, Ge; M= V, Nb, Ta;
X = S, Se). We found that electric fields as low as 2 kV/cm induce an
electronic phase change in these compounds from a Mott insulating state to a
metallic-like state. Our results suggest that this transition belongs to a new
class of resistive switching and might be explained by recent theoretical works
predicting that an insulator to metal transition can be achieved by a simple
electric field in a Mott Insulator. This new type of resistive switching has
potential to build up a new class of Resistive Random Access Memory (RRAM) with
fast writing/erasing times (50 ns to 10 {\mu}s) and resistance ratios \Delta
R/R of the order of 25% at room temperature. | 1304.5607v1 |
2012-06-26 | Measurement of electrical properties of electrode materials for the bakelite Resistive Plate Chambers | Single gap (gas gap 2 mm) bakelite Resistive Plate Chamber (RPC) modules of
various sizes from 10 cm \times 10 cm to 1 m \times 1 m have been fabricated,
characterized and optimized for efficiency and time resolution. Thin layers of
different grades of silicone compound are applied to the inner electrode
surfaces to make them smooth and also to reduce the surface resistivity. In the
silicone coated RPCs an efficiency > 90% and time resolution \sim 2 ns (FWHM)
have been obtained for both the streamer and the avalanche mode of operation.
Before fabrication of detectors the electrical properties such as bulk
resistivity and surface resistivity of the electrode materials are measured
carefully. Effectiveness of different silicone coating in modifying the surface
resistivity was evaluated by an instrument developed for monitoring the I-V
curve of a high resistive surface. The results indicate definite correlation of
the detector efficiency for the atmospheric muons and the RPC noise rates with
the surface resistivity and its variation with the applied bias voltage. It was
also found that the surface resistivity varies for different grades of silicone
material applied as coating, and the results are found to be consistent with
the detector efficiency and noise rate measurements done with these RPCs. | 1206.5894v1 |
2015-09-21 | Resistive Switching in Nanodevices | Passing current at given threshold voltages through a metal/insulator/metal
sandwich structure device may change its resistive state. Such resistive
switching is unique to nanoscale devices, but its underlying physical mechanism
remains unknown. We show that the different resistive states are due to
different spontaneously charged states, characterized by different `band
bending' solutions of Poisson's equation. For an insulator with mainly donor
type defects, the low-resistivity state is characterized by a negatively
charged insulator due to convex band bending, and the high-resistivity state by
a positively charged insulator due to concave band bending; vice versa for
insulators with mainly acceptor type defects. These multiple solutions coexist
only for nanoscale devices and for bias voltages limited by the switching
threshold values, where the system charge spontaneously changes and the system
switches to another resistive state. We outline the general principles how this
functionality depends on material properties and defect abundance of the
insulator `storage medium', and propose a new magnetic memristor device with
increased storage capacity. | 1509.06169v1 |
2018-06-30 | Nanoscale compositional evolution in complex oxide based resistive memories | Functional oxides based resistive memories are recognized as potential
candidate for the next-generation high density data storage and neuromorphic
applications. Fundamental understanding of the compositional changes in the
functional oxides is required to tune the resistive switching characteristics
for enhanced memory performance. Herein, we present the micro/nano-structural
and compositional changes induced in a resistive oxide memory during resistive
switching. Oxygen deficient amorphous chromium doped strontium titanate
(Cr:$a$-SrTiO$_{3-x}$) based resistance change memories are fabricated in a
Ti/Cr:$a$-SrTiO$_{3-x}$ heterostructure and subjected to different biasing
conditions to set memory states. Transmission electron microscope based
cross-sectional analyses of the memory devices in different memory states shows
that the micro/nano-structural changes in amorphous complex oxide and
associated redox processes define the resistive switching behavior. These
experimental results provide insights and supporting material for Ref. [1]. | 1807.00185v1 |
2018-06-04 | Atomistic Study of the Electronic Contact Resistivity Between the Half-Heusler Alloys (HfCoSb, HfZrCoSb, HfZrNiSn) and the Metal Ag | Half-Heusler(HH) alloys have shown promising thermoelectric properties in the
medium and high temperature range. To harness these material properties for
thermoelectric applications, it is important to realize electrical contacts
with low electrical contact resistivity. However, little is known about the
detailed structural and electronic properties of such contacts, and the
expected values of contact resistivity. Here, we employ atomistic ab initio
calculations to study electrical contacts in a subclass of HH alloys consisting
of the compounds HfCoSb, HfZrCoSb, and HfZrNiSn. By using Ag as a prototypical
metal, we show that the termination of the HH material critically determines
the presence or absence of strong deformations at the interface. Our study
includes contacts to doped materials, and the results indicate that the p-type
materials generally form ohmic contacts while the n-type materials have a small
Schottky barrier. We calculate the temperature dependence of the contact
resistivity in the low to medium temperature range and provide quantitative
values that set lower limits for these systems. | 1806.01375v1 |
2009-01-28 | Carbon Based Resistive Memory | We propose carbon as new resistive memory material for non-volatile memories
and compare three allotropes of carbon, namely carbon nanotubes, graphene-like
conductive carbon and insulating carbon for their possible application as
resistance-change material in high density non-volatile memories. Repetitive
high-speed switching and the potential for multi-level programming have been
successfully demonstrated. | 0901.4439v1 |
2016-01-31 | Josephson-like Colossal Resistive Switching in Nanocrystalline Y-Ba-Cu-O at Room Temperature | In this paper, we present data for two nanocrystalline YBa2Cu3O7-x (YBCO)
samples which both exhibit Josephson-like Colossal Resistive Switching (JCRS)
in voltage-current (V-I) traces from 4.2 K up to room temperature, in magnetic
fields up to 8 T. We report Josephson-like hysteresis for both positive and
negative current that has not been observed before in colossal resistive
switching materials. Non-zero resistance was measured in transport measurements
at all temperatures. At low temperatures (< 90 K), we also observed the usual
properties for YBCO including weak superconducting and paramagnetic behavior,
measured using ac susceptibility and magnetization measurements. The
resistivity of these nanocrystalline samples is 3 orders of magnitude higher
than standard polycrystalline materials at 300 K and the temperature dependence
semiconductor-like. We cannot rule out the possibility that these materials
contain a superconducting component responsible for the JCRS behavior at room
temperature. | 1602.00271v3 |
2013-08-28 | First studies with the Resistive-Plate WELL gaseous multiplier | We present the results of first studies of the Resistive Plate WELL (RPWELL):
a single-faced THGEM coupled to a copper anode via a resistive layer of high
bulk resistivity. We explored various materials of different bulk resistivity
(10^9 - 10^12 Ohm cm) and thickness (0.4 - 4 mm). Our most successful
prototype, with a 0.6 mm resistive plate of ~10^9 Ohm cm, achieved gains of up
to 10^5 with 8 keV x-ray in Ne/5%CH4; a minor 30% gain drop occurred with a
rate increase from 10 to 10^4 Hz/mm^2. The detector displayed a full
"discharge-free" operation--even when exposed to high primary ionization
events. We present the RPWELL detector concept and compare its performance to
that of other previously explored THGEM configurations--in terms of gain, its
curves, dependence on rate, and the response to high ionization. The robust
Resistive Plate WELL concept is a step forward in the Micro-Pattern
Gas-Detector family, with numerous potential applications. | 1308.6152v1 |
2021-02-07 | Quantum Conductors Formation and Resistive Switching Memory Effects in Zirconia Nanotubes | The development prospects of memristive elements for non-volatile memory with
use of the metal-dielectric-metal sandwich structures with a thin oxide layer
are due to the possibility of reliable forming the sustained functional states
with quantized resistance. In the paper we study the properties of fabricated
memristors based on the non-stoichiometric $ZrO_2$ nanotubes in different
resistive switching modes. Anodic oxidation of the $Zr$ foil has been used to
synthesize a zirconia layer of $1.7$ $\mu$$m$ thickness, consisting of an
ordered array of vertically oriented nanotubes with outer diameter of 75 nm.
$Zr/ZrO_2/Au$ sandwich structures have been fabricated by mask magnetron
deposition. The effects of resistive switching in the $Zr/ZrO_2/Au$ memristors
in unipolar and bipolar modes have been investigated. The resistance ratios
$\geq3\cdot10^4$ between high-resistance (HRS) and low-resistance (LRS) states
have been evaluated. It has been founded the conductivity of LRS is quantized
in a wide range with minimum value of $0.5G_0=38.74$ $\mu$$S$ due to the
formation of quantum conductors based on oxygen vacancies ($V_O$). Resistive
switching mechanisms of $Zr/ZrO_2/Au$ memristors with allowing for migration of
$V_O$ in an applied electric field have been proposed. It has been shown that
the ohmic type and space charge limited conductivities are realized in the LRS
and HRS, correspondingly. We present the results which can be used for
development of effective memristors based on functional $Zr/ZrO_2/Au$
nanolayered structure with multiple resistive states and high resistance ratio. | 2102.03764v1 |
2004-07-16 | Negative Differential Resistivity and Positive Temperature Coefficient of Resistivity effect in the diffusion limited current of ferroelectric thin film capacitors | We present a model for the leakage current in ferroelectric thin- film
capacitors which explains two of the observed phenomena that have escaped
satisfactory explanation, i.e. the occurrence of either a plateau or negative
differential resistivity at low voltages, and the observation of a Positive
Temperature Coefficient of Resistivity (PTCR) effect in certain samples in the
high-voltage regime. The leakage current is modelled by considering a
diffusion-limited current process, which in the high-voltage regime recovers
the diffusion-limited Schottky relationship of Simmons already shown to be
applicable in these systems. | 0407428v1 |
2015-05-18 | Nonpolar resistive memory switching with all four possible resistive switching modes in amorphous ternary rare earth LaHoO3 thin films | We studied the resistive memory switching in pulsed laser deposited amorphous
LaHoO3 (LHO) thin films for non-volatile resistive random access memory (RRAM)
applications. Nonpolar resistive switching (RS) was achieved in PtLHOPt memory
cells with all four possible RS modes ( positive unipolar, positive bipolar,
negative unipolar, and negative bipolar) having high RON and ROFF ratios (in
the range of 104 to 105) and non-overlapping switching voltages (set voltage,
VON 3.6 to 4.2 V and reset voltage, VOFF 1.3 to 1.6 V) with a small variation
of about 5 to 8 percent. X ray photoelectron spectroscopic studies together
with temperature dependent switching characteristics revealed the formation of
metallic holmium (Ho) and oxygen vacancies (VO) constituted conductive
nanofilaments (CNFs) in the low resistance state (LRS). Detailed analysis of
current versus voltage characteristics further corroborated the formation of
CNFs based on metal like (Ohmic) conduction in LRS. Simmons Schottky emission
was found to be the dominant charge transport mechanism in the high resistance
state. | 1505.04690v1 |
2019-07-23 | Electron transport in high-entropy alloys: Al$_{x}$CrFeCoNi as a case study | The high-entropy alloys Al$_{x}$CrFeCoNi exist over a broad range of Al
concentrations ($0 < x < 2$). With increasing Al content their structure is
changed from the fcc to bcc phase. We investigate the effect of such structural
changes on transport properties including the residual resistivity and the
anomalous Hall resistivity. We have performed a detailed comparison of the
first-principles simulations with available experimental data. We show that the
calculated residual resistivities for all studied alloy compositions are in a
fair agreement with available experimental data as concerns both the
resistivity values and concentration trends. We emphasize that a good agreement
with experiment was obtained also for the anomalous Hall resistivity. We have
completed study by estimation of the anisotropic magnetoresistance,
spin-disorder resistivity, and Gilbert damping. The obtained results prove that
the main scattering mechanism is due to the intrinsic chemical disorder whereas
the effect of spin polarization on the residual resistivity is appreciably
weaker. | 1907.09731v1 |
2018-04-14 | Investigating the Composite/Metal Interface and its Influence on the Electrical Resistance Measurement | The advantages introduced by carbon fiber reinforced polymer (CFRP)
composites has made them an appropriate choice in many applications and an
ideal replacement for conventional materials. The benefits using CFRP
composites are due to their lightweight, high stiffness, as well as corrosion
resistance. For this reason, there is a fast growing trend in using CFRP
composites for aircraft and wind turbine structural applications. The
replacement of the conventional aerospace-grade metal alloys (aluminum,
titanium, magnesium, etc.) with CFRP composites results in new challenges. For
example, an aircraft during flight is prone to be struck by lightning. To
withstand the injection of such massive amount of energy, adequate electrical
properties, mainly electrical conductivity, is required. In fact, electrical
conductance (or its reciprocal, resistance) is a critical parameter
representing any material change and it can be considered an index for health
monitoring. In this paper, AS4/8552 carbon/epoxy laminated composites were
injected with two types of electrical currents, impulse current and direct
current. The change in measured electrical resistance was recorded. A
significant resistance drop occurred after electrical current injections.
Furthermore, four-point flexural tests were performed on these composites to
correlate an electrical resistance change with a potential flexural property
change. There was no clear trend between a resistance change and flexural
strength/modulus change of the test coupons, regardless of current injection.
However, it was observed that the injection of the current affects the contact
resistance such that its resistance decreases. | 1804.06246v1 |
2018-08-09 | Underlying burning resistant mechanisms for titanium alloy | The "titanium fire" as produced during high pressure and friction is the
major failure scenario for aero-engines. To alleviate this issue, Ti-V-Cr and
Ti-Cu-Al series burn resistant titanium alloys have been developed. However,
which burn resistant alloy exhibit better property with reasonable cost needs
to be evaluated. This work unveils the burning mechanisms of these alloys and
discusses whether burn resistance of Cr and V can be replaced by Cu, on which
thorough exploration is lacking. Two representative burn resistant alloys are
considered, including Ti14(Ti-13Cu-1Al-0.2Si) and
Ti40(Ti-25V-15Cr-0.2Si)alloys. Compared with the commercial non-burn resistant
titanium alloy, i.e., TC4(Ti-6Al-4V)alloy, it has been found that both Ti14 and
Ti40 alloys form "protective" shields during the burning process. Specifically,
for Ti14 alloy, a clear Cu-rich layer is formed at the interface between
burning product zone and heat affected zone, which consumes oxygen by producing
Cu-O compounds and impedes the reaction with Ti-matrix. This work has
established a fundamental understanding of burning resistant mechanisms for
titanium alloys. Importantly, it is found that Cu could endow titanium alloys
with similar burn resistant capability as that of V or Cr, which opens a
cost-effective avenue to design burn resistant titanium alloys. | 1808.02976v1 |
2005-10-03 | Buffer-Enhanced Electrical-Pulse-Induced-Resistive Memory Effect in Thin Film Perovskites | A multilayer perovskite thin film resistive memory device has been developed
comprised of: a Pr0.7Ca0.3MnO3 (PCMO) perovskite oxide epitaxial layer on a
YBCO bottom thin film electrode; a thin yttria stabilized zirconia (YSZ) buffer
layer grown on the PCMO layer, and a gold thin film top electrode. The
multi-layer thin film lattice structure has been characterized by XRD and TEM
analyses showing a high quality heterostructure. I-AFM analysis indicated nano
granular conductivity distributed uniformly throughout the PCMO film surface.
With the addition of the YSZ buffer layer, the pulse voltage needed to switch
the device is significantly reduced and the resistance-switching ratio is
increased compared to a non-buffered resistance memory device, which is very
important for the device fabrication. The magnetic field effect on the
multilayer structure resistance at various temperatures shows CMR behavior for
both high and low resistance states implying a bulk material component to the
switch behavior. | 0510060v1 |
2020-04-24 | Solution-processed silver sulphide nanocrystal film for resistive switching memories | Resistive switching memories allow electrical control of the conductivity of
a material, by inducing a high resistance (OFF) or a low resistance (ON) state,
using electrochemical and ion transport processes. As alternative to high
temperature and vacuum-based physical sulphurization methods of silver (Ag),
here we propose, as resistive switching medium, a layer built from colloidal
Ag$_{2-x}$S nanocrystals -compatible with solution-processed approaches. The
effect of the electrode size (from macro- to micro-scale), composition (Ag, Ti
and Pt) and geometry on the device performance together with the
electrochemical mechanisms involved are evaluated. We achieved an optimized
Ag/Ti bowtie proof-of-concept configuration by e-beam lithography, which
fulfils the general requirements for ReRAM devices in terms of low power
consumption and reliable $I_{ON}/I_{OFF}$ ratio. This configuration
demonstrates reproducible switching between ON and OFF states with data
endurance of at least 20 cycles; and an $I_{ON}/I_{OFF}$ ratio up to 10$^3$ at
low power consumption (0.1V readout), which outperforms previous results in
literature for devices with resistive layers fabricated from silver
chalcogenide nanoparticles. | 2004.11875v1 |
2005-12-22 | Measurement of Local Reactive and Resistive Photoresponse of a Superconducting Microwave Device | We propose and demonstrate a spatial partition method for the high-frequency
photo-response of superconducting devices correlated with inductive and
resistive changes in microwave impedance. Using a laser scanning microscope, we
show that resistive losses are mainly produced by local defects at microstrip
edges and by intergrain weak links in the high-temperature superconducting
material. These defects initiate nonlinear high-frequency response due to
overcritical current densities and entry of vortices. | 0512572v1 |
2002-10-28 | Nanometer-Scale Metallic Grains Connected with Atomic-Scale Conductors | We describe a technique for connecting a nanometer-scale gold grain to leads
by atomic-scale gold point contacts. These devices differ from previous
metallic quantum dots in that the conducting channels are relatively
well-transmitting. We investigate the dependence of the Coulomb blockade on
contact resistance. The high-resistance devices display Coulomb blockade and
the low-resistance devices display a zero-bias conductance dip, both in
quantitative agreement with theory. We find that in the intermediate regime,
where the sample resistance is close to $h/e^2$, the I-V curve displays a
Coulomb staircase with symmetric contact capacitances. | 0210620v1 |
2004-08-05 | Influence of Grain size on the Electrical Properties of ${\rm Sb_2Te_3}$ Polycrystalline Films | Resistance of vacuum deposited ${\rm Sb_2Te_3}$ films of thickness between
100-500nm has been measured in vacuum. It is found that the resistance of the
polycrystalline films strongly depends on the grain size and inter-granular
voids. The charge carrier are shown to cross this high resistivity inter-
granular void by ohmic conduction. The barrier height as well as temperature
coefficient of resistance are also shown to depend on the grain size and inter-
grain voids. | 0408116v1 |
2008-05-03 | Resistance Quenching in Graphene Interconnects | We investigated experimentally the high-temperature electrical resistance of
graphene interconnects. The test structures were fabricated using the focused
ion beam from the single and bi-layer graphene produced by mechanical
exfoliation. It was found that as temperature increases from 300 to 500K the
resistance of the single- and bi-layer graphene interconnects drops down by 30%
and 70%, respectively. The quenching and temperature dependence of the
resistance were explained by the thermal generation of the electron-hole pairs
and acoustic phonon scattering. The obtained results are important for the
proposed applications of graphene as interconnects in integrated circuits. | 0805.0334v1 |
2008-05-12 | Negative differential resistance and pulsed current induced multi-level resistivity switching in charge ordered and disordered manganites | We have investigated direct and pulsed current induced electroresistance in
two manganites with different electronic and magnetic ground states:
charge-orbital ordered 50 % Ca doped NdMnO3 and 50 % Mn doped LaNiO3. It has
been shown that negative differential resistance observed at high current
density in these compounds is related to Joule heating. However, bi-level and
multi-level resistivity switching induced by variations in pulse width and
pulse period at low current density can not be attributable to Joule heating
alone. We discuss possible origins. | 0805.1643v1 |
2012-07-13 | Enhanced Resolution of Poly-(Methyl Methacrylate) Electron Resist by Thermal Processing | Granular nanostructure of electron beam resist had limited the ultimate
resolution of electron beam lithography. We report a thermal process to achieve
a uniform and homogeneous amorphous thin film of poly methyl methacrylate
electron resist. This thermal process consists of a short time-high temperature
backing process in addition to precisely optimized development process
conditions. Using this novel process, we patterned arrays of holes in a metal
film with diameter smaller than 5nm. In addition, line edge roughness and
surface roughness of the resist reduced to 1nm and 100pm respectively. | 1207.3183v1 |
2016-11-12 | Anomalous resistivity upturn in epitaxial L21-Co2MnAl films | We report the controllable growth and the intriguing transport behavior of
high-spin-polarization epitaxial L21-Co2MnAl films, which exhibit a
low-temperature (T) resistivity upturn with pronounced T1/2 dependence, close
relevance to structural disorder, and robust independence of magnetic fields.
The resistivity upturn turns out to be qualitatively contradictory to weak
localization, particle-particle channel electron-electron interaction (EEI),
and orbital two-channel Kondo effect, leaving a three-dimensional particle-hole
channel EEI the most likely physical source. Our result highlights a
considerable tunability of the structural and electronic disorder of magnetic
films by varying growth temperature, affording unprecedented insights into the
spin polarization and the resistivity upturn. | 1611.04013v2 |
2011-04-06 | Temperature dependence of contact resistance of Au-Ti-Pd2Si-n+-Si ohmic contacts | We investigated temperature dependence of contact resistance of an
Au-Ti-Pd2Si ohmic contact to heavily doped n+-Si. The contact resistance
increases with temperature owing to conduction through the metal shunts. In
this case, the limiting process is diffusion input of electrons to the metal
shunts. The proposed mechanism of contact resistance formation seems to realize
also in the case of wide-gap semiconductors with high concentration of surface
states and dislocation density in the contact. | 1104.1030v1 |
2021-04-25 | Electrical resistivity in 2d Kondo lattice systems | I extend the calculations represented in \cite{konav} regarding the
resistivity in Kondo lattice materials from $3d$ syatem to $2d$ systems. In the
present work I consider a 2d system, and memory function is computed. However,
results found in 2d case are different from 3d system . I find that in $2d$ in
low temperature regime($ k_{B}T\ll \mu_d$) resistivity shows power
law($\frac{1}{T}$) behaviour and in the high temeprature regime($
k_{B}T\gg\mu_d$) resistivity varies linearly with temperature. In $3d$ these
behaviours are as $\frac{1}{T}$ and as $T^{\frac{3}{2}}$ respectively. | 2104.12129v1 |
2008-01-22 | Abnormal Resistance Switching Behaviors of NiO Thin Films: Possible Occurrence of Simultaneous Formation and Rupture of Conducting Channels | We report the detailed current-voltage (I-V) characteristics of resistance
switching in NiO thin films. In unipolar resistance switching, it is commonly
believed that conducting filaments will rupture when NiO changes from a low
resistance to a high resistance state. However, we found that this resistance
switching can sometimes show abnormal behavior during voltage- and
current-driven I-V measurements. We used the random circuit breaker network
model to explain how abnormal switching behaviors could occur. We found that
this resistance change can occur via a series of avalanche processes, where
conducting filaments could be formed as well as ruptured. | 0801.3323v1 |
2009-08-12 | Large 1/f noise of unipolar resistance switching and its percolating nature | We investigated the 1/f noise of Pt/NiO/Pt capacitors that show unipolar
resistance switching. When they were switched from the low to high resistance
states, the power spectral density of the voltage fluctuation was increased by
approximately five orders of magnitude. At 100 K, the relative resistance
fluctuation, SR/R2, in the low resistance state displayed a power law
dependence on the resistance R with exponent w = 1.6. This behavior can be
explained by percolation theory; however, at higher temperatures or near the
switching voltage, SR/R2 becomes enhanced further. This large 1/f noise can be
therefore an important problem in the development of resistance random access
memory devices. | 0908.1606v1 |
2017-04-11 | Scalability of Voltage-Controlled Filamentary and Nanometallic Resistance Memories | Much effort has been devoted to device and materials engineering to realize
nanoscale resistance random access memory (RRAM) for practical applications,
but there still lacks a rational physical basis to be relied on to design
scalable devices spanning many length scales. In particular, the critical
switching criterion is not clear for RRAM devices in which resistance changes
are limited to localized nanoscale filaments that experience concentrated heat,
electric current and field. Here, we demonstrate voltage-controlled resistance
switching for macro and nano devices in both filamentary RRAM and nanometallic
RRAM, the latter switches uniformly and does not require forming. As a result,
using a constant current density as the compliance, we have achieved
area-scalability for the low resistance state of the filamentary RRAM, and for
both the low and high resistance states of the nanometallic RRAM. This finding
will help design area-scalable RRAM at the nanoscale. | 1704.03415v1 |
2021-10-07 | A Modern-day Alchemy: Double Glow Plasma Surface Metallurgy Technology | In the long history of science and technology development, one goal is to
diffuse solid alloy elements into the surface of steel materials to form
surface alloys with excellent physical and chemical properties. On the basis of
plasma nitriding technology, double glow plasma surface metallurgy technology
has answered this challenge. This technology, which seems to be a modern-day
alchemy, can use any element in the periodic table of chemical elements,
including solid metal elements and their combinations, to form many types of
surface alloyed layers with high hardness, wear resistance, corrosion
resistance and high temperature oxidation resistance on various metal
materials. For examples, nickel base alloys, stainless steels and high speed
steels are formed on the surfaces of ordinary carbon steels; and high hardness,
wear resistance and high temperature oxidation resistance alloy are formed on
the surface of titanium alloy.This article briefly introduces the formation and
principle of double glow plasma surface metallurgy technology, and summarizes
the experimental results and industry application. The significance and
development prospect of this technology are discussed. | 2110.03236v1 |
2019-09-15 | Large Resistivity Reduction in Mixed-Valent CsAuBr$_3$ Under Pressure | We report on high-pressure $p \leq 45$ GPa resistivity measurements on the
perovskite-related mixed-valent compound CsAuBr$_3$. The compounds
high-pressure resistivity can be classified into three regions: For low
pressures ($p < 10$ GPa) an insulator to metal transition is observed; between
$p= 10$ GPa and 14 GPa the room temperature resistivity goes through a minimum
and increases again; above $p = 14$ GPa a semiconducting state is observed.
From this pressure up to the highest pressure of $p = 45$ GPa reached in this
experiment, the room-temperature resistivity remains nearly constant. We find
an extremely large resistivity reduction between ambient pressure and 10 GPa by
more than 6 orders of magnitude. This decrease is among the largest reported
changes in the resistivity for this narrow pressure regime. We show - by an
analysis of the electronic band structure evolution of this material - that the
large change in resistivity under pressure in not caused by a crossing of the
bands at the Fermi level. We find that it instead stems from two bands that are
pinned at the Fermi level and that are moving towards one another as a
consequence of the mixed-valent to single-valent transition. This mechanism
appears to be especially effective for the rapid buildup of the density of
states at the Fermi level. | 1909.06874v1 |
2023-02-25 | Peculiarities of electron transport and resistive switching in point contacts on TiSe2, TiSeS and CuxTiSe2 | TiSe2 has received much attention among the transition metals chalcogenides
because of its thrilling physical properties concerning atypical resistivity
behavior, emerging of charge density wave (CDW) state, induced
superconductivity etc. Here, we report discovery of new feature of TiSe2,
namely, observation of resistive switching in voltage biased point contacts
(PCs) based on TiSe2 and its derivatives doped by S and Cu (TiSeS, CuxTiSe2).
The switching is taking place between a low resistive mainly metallic-type
state and a high resistive semiconducting-type state by applying bias voltage
(usually below 0.5V), while reverse switching takes place by applying voltage
of opposite polarity (usually below 0.5V). The difference in resistance between
these two states can reach up to two orders of magnitude at the room
temperature. The origin of the effect can be attributed to the variation of
stoichiometry in PC core due to drift/displacement of Se/Ti vacancies under
high electric field. Additionally, we demonstrated, that heating takes place in
PC core, which can facilitate the electric field induced effect. At the same
time, we did not found any evidence for CDW spectral features in our PC spectra
for TiSe2. The observed resistive switching allows to propose TiSe2 and their
derivatives as the promising materials, e.g., for non-volatile resistive random
access memory (ReRAM) engineering. | 2302.13085v1 |
2021-04-21 | A First-Principles-Based Approach to The High-Throughput Screening of Corrosion-Resistant High Entropy Alloys | The design of corrosion-resistant high entropy alloys (CR-HEAs) is
challenging due to the alloys' virtually astrological composition space. To
facilitate this, efficient and reliable high-throughput exploratory approaches
are needed. Toward this end, the current work reports a first-principles-based
approach exploiting the correlations between work function, surface energy, and
corrosion resistance (i.e., work function and surface energy are, by
definitions, proportional and inversely proportional to an alloy's inherent
corrosion resistance, respectively). Two Bayesian CALPHAD models (or databases)
of work function and surface energy of FCC Co-Cr-Fe-Mn-Mo-Ni are assessed using
discrete surface energies and work functions derived by density-functional
theory (DFT) calculations. The models are then used to rank different
Co-Cr-Fe-Mn-Mo-Ni alloy compositions. It is observed that the ranked alloys
possess chemical traits similar to previously studied corrosion-resistance
alloys, suggesting that the proposed approach can be used to reliably screen
HEAs with potentially good inherent corrosion resistance. | 2104.10590v1 |
2023-04-02 | Percolation-induced resistivity drop in cold-pressed LuH2 | The stoichiometric bulk LuH2 is a paramagnetic metal with high electrical
conductivity comparable to simple metals. Here we show that the resistivity of
cold-pressed (CP) LuH2 samples varies sensitively upon modifying the grain size
or surface conditions via the grinding process, i.e., the CP pellets made of
commercially purchased LuH2 powder remain metallic but exhibit thousands of
times higher resistivity, while additional grinding of LuH2 powders in air
further enhances the resistivity and even results in weakly localized
behaviors. For these CP samples, interestingly, we can occasionally observe
abrupt resistivity drops at high temperatures, which also show dependences on
magnetic fields and electrical current. Measurements of variable-temperature
XRD, magnetic susceptibility, and specific heat exclude the possibilities of
structural, magnetic, and superconducting transitions for the observed
resistivity drops. Instead, we tentatively attribute these above observations
to the presence of insulating layers on the grain surface due to the
modification of hydrogen stoichiometry or the pollution by oxygen/nitrogen.
Percolation of the metallic grains through the insulating surfaces can explain
the sudden drop in resistivity. The present results thus call for caution in
asserting the resistivity drops as superconductivity and invalidate the
background subtraction in analyzing the resistivity data. | 2304.00558v1 |
2017-07-28 | High-temperature quantum oscillations of the Hall resistance in bulk Bi$_2$Se$_3$ | Helically spin-polarized Dirac fermions (HSDF) in protected topological
surface states (TSS) are of high interest as a new state of quantum matter. In
three-dimensional (3D) materials with TSS, electronic bulk states often mask
the transport properties of HSDF. Recently, the high-field Hall resistance and
low-field magnetoresistance indicate that the TSS may coexist with a layered
two-dimensional electronic system (2DES). Here, we demonstrate quantum
oscillations of the Hall resistance at temperatures up to 50 K in bulk
Bi$_2$Se$_3$ with a high electron density $n$ of about $2\!\cdot\!10^{19}$
cm$^{-3}$. From the angular and temperature dependence of the Hall resistance
and the Shubnikov-de Haas oscillations we identify 3D and 2D contributions to
transport. Angular resolved photoemission spectroscopy proves the existence of
TSS. We present a model for Bi$_2$Se$_3$ and suggest that the coexistence of
TSS and 2D layered transport stabilizes the quantum oscillations of the Hall
resistance. | 1707.09181v1 |
2005-11-15 | Unconventional Hall effect in oriented Ca$_3$Co$_4$O$_9$ thin films | Transport properties of the good thermoelectric misfit oxide
Ca$_3$Co$_4$O$_9$ are examined. In-plane resistivity and Hall resistance
measurements were made on epitaxial thin films which were grown on {\it c}-cut
sapphire substrates using the pulsed laser deposition technique. Interpretation
of the in-plane transport experiments relates the substrate-induced strain in
the resulting film to single crystals under very high pressure ($\sim$ 5.5 GPa)
consistent with a key role of strong electronic correlation. They are confirmed
by the measured high temperature maxima in both resistivity and Hall
resistance. While hole-like charge carriers are inferred from the Hall effect
measurements over the whole investigated temperature range, the Hall resistance
reveals a non monotonic behavior at low temperatures that could be interpreted
with an anomalous contribution. The resulting unconventional temperature
dependence of the Hall resistance seems thus to combine high temperature
strongly correlated features above 340 K and anomalous Hall effect at low
temperature, below 100 K. | 0511374v1 |
2013-10-21 | Micro Pixel Chamber with resistive electrodes for spark reduction | The Micro Pixel Chamber (mu-PIC) using resistive electrodes has been
developed and tested. The surface cathodes are made from resistive material, by
which the electrical field is reduced when large current is flowed.
Two-dimensional readouts are achieved by anodes and pickup electrodes, on which
signals are induced. High gas gain (> 60000) was measured using 55Fe (5.9 keV)
source, and very intensive spark reduction was attained under fast neutron. The
spark rate of resistive mu-PIC was only 10^-4 times less than that of
conventional mu-PIC at the gain of 10^4. With these developments, a new MPGD
with no floating structure is achieved, with enough properties of both high
gain and good stability to detect MIP particles. In addition, mu-PIC can be
operated with no HV applied on anodes by using resistive cathodes. Neither AC
coupling capacitors nor HV pull up resisters are needed for any anode
electrode. Signal readout is drastically simplified by that configuration. | 1310.5550v1 |
2023-11-28 | Quantifying the contribution of material and junction resistances in nano-networks | Networks of nanowires and nanosheets are important for many applications in
printed electronics. However, the network conductivity and mobility are usually
limited by the inter-particle junction resistance, a property that is
challenging to minimise because it is difficult to measure. Here, we develop a
simple model for conduction in networks of 1D or 2D nanomaterials, which allows
us to extract junction and nanoparticle resistances from
particle-size-dependent D.C. resistivity data of conducting and semiconducting
materials. We find junction resistances in porous networks to scale with
nanoparticle resistivity and vary from 5 Ohm for silver nanosheets to 25 GOhm
for WS2 nanosheets. Moreover, our model allows junction and nanoparticle
resistances to be extracted from A.C. impedance spectra of semiconducting
networks. Impedance data links the high mobility (~7 cm2/Vs) of aligned
networks of electrochemically exfoliated MoS2 nanosheets to low junction
resistances of ~670 kOhm. Temperature-dependent impedance measurements allow us
to quantitatively differentiate intra-nanosheet phonon-limited band-like
transport from inter-nanosheet hopping for the first time. | 2311.16740v1 |
2016-02-04 | Low-Resistance 2D/2D Ohmic Contacts: A Universal Approach to High-Performance WSe2, MoS2, and MoSe2 Transistors | We report a new strategy for fabricating 2D/2D low-resistance ohmic contacts
for a variety of transition metal dichalcogenides (TMDs) using van der Waals
assembly of substitutionally doped TMDs as drain/source contacts and TMDs with
no intentional doping as channel materials. We demonstrate that few-layer WSe2
field-effect transistors (FETs) with 2D/2D contacts exhibit low contact
resistances of ~ 0.3 k ohm.um, high on/off ratios up to > 109, and high drive
currents exceeding 320 uA um-1. These favorable characteristics are combined
with a two-terminal field-effect hole mobility ~ 2x102 cm2 V-1 s-1 at room
temperature, which increases to >2x103 cm2 V-1 s-1 at cryogenic temperatures.
We observe a similar performance also in MoS2 and MoSe2 FETs with 2D/2D drain
and source contacts. The 2D/2D low-resistance ohmic contacts presented here
represent a new device paradigm that overcomes a significant bottleneck in the
performance of TMDs and a wide variety of other 2D materials as the channel
materials in post-silicon electronics. | 1602.01790v1 |
2013-12-30 | Deviations from Matthiessen rule and resistivity saturation effects in Gd and Fe | According to earlier first-principles calculations, the spin-disorder
contribution to the resistivity of rare-earth metals in the paramagnetic state
is strongly underestimated if Matthiessen's rule is assumed to hold. To
understand this discrepancy, the resistivity of paramagnetic Fe and Gd is
evaluated by taking into account both spin and phonon disorder. Calculations
are performed using the supercell approach within the linear muffin-tin orbital
method. Phonon disorder is modeled by introducing random displacements of the
atomic nuclei, and the results are compared with the case of fictitious
Anderson disorder. In both cases the resistivity shows a nonlinear dependence
on the square of the disorder potential, which is interpreted as a resistivity
saturation effect. This effect is much stronger in Gd than in Fe. The
non-linearity makes the phonon and spin-disorder contributions to the
resistivity non-additive, and the standard procedure of extracting the
spin-disorder resistivity by extrapolation from high temperatures becomes
ambiguous. An "apparent" spin-disorder resistivity obtained through such
extrapolation is in much better agreement with experiment compared to the
results obtained by considering only spin disorder. By analyzing the spectral
function of the paramagnetic Gd in the presence of Anderson disorder, the
resistivity saturation is explained by the collapse of a large area of the
Fermi surface due to the disorder-induced mixing between the electronic and
hole sheets. | 1312.7802v1 |
2016-11-08 | Controlling friction in a manganite surface by resistive switching | We report a significant change in friction of a $\rm La_{0.55}Ca_{0.45}MnO_3$
thin film measured as a function of the materials resistive state under
ultrahigh vacuum conditions at room temperature by friction force microscopy.
While friction is high in the insulating state, it clearly changes to lower
values if the probed local region is switched to the conducting state via
nanoscale resistance switching. Thus we demonstrate active control of friction
without having to change the temperature or pressure. Upon switching back to an
insulating state the friction increases again. The results are discussed in the
framework of electronic friction effects and electrostatic interactions. | 1611.02684v1 |
2019-10-05 | Metamaterial insertions for resistive-wall beam-coupling impedance reduction | Resistive-wall impedance usually constitutes a significant percentage of the
total beamcoupling impedance budget of an accelerator. Reduction techniques
often entail high electrical-conductivity coatings. This paper investigates the
use of negative-permittivity or negative-permeability materials for sensibly
reducing or theoretically nearly cancelling resistive-wall impedance. The
proposed approach is developed by means of an equivalent transmission-line
model. The effectiveness of such materials is benchmarked for the negative
permeability case with experimental measurements in two frequency bandwidths.
This first-stage study opens the possibility of considering metamaterials for
impedance mitigation. | 1910.02246v1 |
2020-07-07 | Resistivity saturation in an electron-doped cuprate | We report the observation of resistivity saturation in lightly doped ($x\sim
0.10)$ as-grown samples of the electron-doped cuprate La$_{2-x}$Ce$_x$CuO$_4$
(LCCO). The saturation occurs at resistivity values roughly consistent with the
phenomenological Mott-Ioffe-Regel criterion once the low effective carrier
density of these materials is included in the analysis. These results imply
that, at least for light doping, the high-temperature metallic phase of these
materials is not necessarily strange and may be understood as simply a
low-density metal. | 2007.03685v1 |
2015-06-24 | Resonant tunneling in a quantum oxide superlattice | Resonant tunnelling is a quantum mechanical process that has long been
attracting both scientific and technological attention owing to its intriguing
underlying physics and unique applications for high-speed electronics. The
materials system exhibiting resonant tunnelling, however, has been largely
limited to the conventional semiconductors, partially due to their excellent
crystalline quality. Here we show that a deliberately designed transition metal
oxide superlattice exhibits a resonant tunnelling behaviour with a clear
negative differential resistance. The tunnelling occurred through an atomically
thin, lanthanum {\delta}-doped SrTiO3 layer, and the negative differential
resistance was realized on top of the bipolar resistance switching typically
observed for perovskite oxide junctions. This combined process resulted in an
extremely large resistance ratio (~10^5) between the high and low-resistance
states. The unprecedentedly large control found in atomically thin
{\delta}-doped oxide superlattices can open a door to novel oxide-based
high-frequency logic devices. | 1506.07583v1 |
2021-08-26 | An investigation of high entropy alloy conductivity using first-principles calculations | The Kubo-Greenwood equation, in combination with the first-principles
Korringa-Kohn-Rostoker Coherent Potential Approximation (KKR-CPA) can be used
to calculate the DC residual resistivity of random alloys at T = 0 K. We
implemented this method in a multiple scattering theory based ab initio
package, MuST, and applied it to the ab initio study of the residual
resistivity of the high entropy alloy Al$_x$CoCrFeNi as a function of $x$. The
calculated resistivities are compared with experimental data. We also predict
the residual resistivity of refractory high entropy alloy MoNbTaV$_x$W. The
calculated resistivity trends are also explained using theoretical arguments. | 2108.11739v1 |
2024-01-27 | Influence od the process parameters on the quality a efficiency of the resistance spot welding process of advanced high strength complex phase stells | The effects of electrical characteristics of an inverter combined with main
welding parameters on the resistance spot weldability of advanced high strength
steels AHSS CP1000 is investigated. | 2401.15457v1 |
2016-02-22 | The effect of Ta oxygen scavenger layer on HfO$_2$-based resistive switching behavior: thermodynamic stability, electronic structure, and low-bias transport | Reversible resistive switching between high-resistance and low-resistance
states in metal-oxide-metal heterostructures makes them very interesting for
applications in random access memories. While recent experimental work has
shown that inserting a metallic "oxygen scavenger layer" between the positive
electrode and oxide improves device performance, the fundamental understanding
of how the scavenger layer modifies heterostructure properties is lacking. We
use density functional theory to calculate thermodynamic properties and
conductance of TiN/HfO$_2$/TiN heterostructures with and without Ta scavenger
layer. First, we show that Ta insertion lowers the formation energy of
low-resistance states. Second, while the Ta scavenger layer reduces the
Schottky barrier height in the high-resistance state by modifying the interface
charge at the oxide-electrode interface, the heterostructure maintains a high
resistance ratio between high- and low-resistance states. Finally, we show that
the low-bias conductance of device on-states becomes much less sensitive to the
spatial distribution of oxygen removed from the HfO$_2$ in the presence of the
Ta layer. By providing fundamental understanding of the observed improvements
with scavenger layers, we open a path to engineer interfaces with oxygen
scavenger layers to control and enhance device performance. In turn, this may
enable the realization of a non-volatile low-power memory technology with
concomitant reduction in energy consumption by consumer electronics and
significant benefits to society. | 1602.06793v1 |
2002-09-04 | Electrical resistivity at large temperatures: Saturation and lack thereof | Many transition metal compounds show saturation of the resistivity at high
temperatures, T, while the alkali-doped fullerenes and the high-Tc cuprates are
usually considered to show no saturation. We present a model of transition
metal compounds, showing saturation, and a model of alkali-doped fullerenes,
showing no saturation. To analyze the results we use the f-sum rule, which
leads to an approximate upper limit for the resistivity at large T. For some
systems and at low T, the resistivity increases so rapidly that this upper
limit is approached for experimental T. The resistivity then saturates. For a
model of transition metal compounds with weakly interacting electrons, the
upper limit corresponds to a mean free path consistent with the Ioffe-Regel
condition. For a model of the high Tc cuprates with strongly interacting
electrons, however, the upper limit is much larger than the Ioffe-Regel
condition suggests. Since this limit is not exceeded by experimental data, the
data are consistent with saturation also for the cuprates. After "saturation"
the resistivity usually grows slowly. For the alkali-doped fullerenes,
"saturation" can be considered to have happened already for T=0, due to
orientational disorder. For these systems, however, the resistivity grows so
rapidly after "saturation" that this concept is meaningless. This is due to the
small band width and to the coupling to the level energies of the important
phonons. | 0209099v1 |
2023-12-26 | Corrosion-resistant aluminum alloy design through machine learning combined with high-throughput calculations | Efficiently designing lightweight alloys with combined high corrosion
resistance and mechanical properties remains an enduring topic in materials
engineering. To this end, machine learning (ML) coupled ab-initio calculations
is proposed within this study. Due to the inadequate accuracy of conventional
stress-strain ML models caused by corrosion factors, a novel reinforcement
self-learning ML algorithm (accuracy R2 >0.92) is developed. Then, a strategy
that integrates ML models, calculated energetics and mechanical moduli is
implemented to optimize the Al alloys. Next, this Computation Designed
Corrosion-Resistant Al alloy is fabricated that verified the simulation. The
performance (elongation reaches ~30%) is attributed to the H-captured Al-Sc-Cu
phases (-1.44 eV H-1) and Cu-modified {\eta}/{\eta}' precipitation inside the
grain boundaries (GBs). The developed Al-Mg-Zn-Cu interatomic potential (energy
accuracy 6.50 meV atom-1) proves the cracking resistance of the GB region
enhanced by Cu-modification. Conceptually, our strategy is of practical
importance for designing new alloys exhibiting corrosion resistance and
mechanical properties. | 2312.15899v1 |
2001-03-01 | Properties of Pt Schottky Type Contacts On High-Resistivity CdZnTe Detectors | In this paper we present studies of the I-V characteristics of CdZnTe
detectors with Pt contacts fabricated from high-resistivity single crystals
grown by the high-pressure Brigman process. We have analyzed the experimental
I-V curves using a model that approximates the CZT detector as a system
consisting of a reversed Schottky contact in series with the bulk resistance.
Least square fits to the experimental data yield 0.78-0.79 eV for the Pt-CZT
Schottky barrier height, and <20 V for the voltage required to deplete a 2 mm
thick CZT detector. We demonstrate that at high bias the thermionic current
over the Schottky barrier, the height of which is reduced due to an interfacial
layer between the contact and CZT material, controls the leakage current of the
detectors. In many cases the dark current is not determined by the resistivity
of the bulk material, but rather the properties of the contacts; namely by the
interfacial layer between the contact and CZT material. | 0103005v1 |
2010-01-27 | An anomalous butterfly-shaped magnetoresistance loop in an alloy, Tb4LuSi3 | Magnetic-field (H) induced first-order magnetic transition and the assiciated
electronic phase-separation phenomena are active topics of research in
magnetism. Magnetoresistance (MR) is a key property to probe these phenomena
and, in literature, a butterfly-shaped MR loop has been noted while cycling the
field, with the envelope curve lying below the virgin curve in MR versus H
plots of such materials. Here, we report an opposite behavior of MR loop for an
alloy, Tb4LuSi3, at low temperatures (<<20 K) in the magnetically ordered
state. Such an anomalous curve reveals unexpected domination of higher
resistive high-field phase in electronic conduction, unlike in other materials
where conducion is naturally by low-resistive high-field phase that follows
first-order transition. The observed features reveal an unusual electronic
phase separation, namely involving high-resistive high-field phase and
low-resistive virgin phase. | 1001.4942v1 |
2006-03-31 | Clustering of vacancy defects in high-purity semi-insulating SiC | Positron lifetime spectroscopy was used to study native vacancy defects in
semi-insulating silicon carbide. The material is shown to contain (i) vacancy
clusters consisting of 4--5 missing atoms and (ii) Si vacancy related
negatively charged defects. The total open volume bound to the clusters
anticorrelates with the electrical resistivity both in as-grown and annealed
material. Our results suggest that Si vacancy related complexes compensate
electrically the as-grown material, but migrate to increase the size of the
clusters during annealing, leading to loss of resistivity. | 0603849v3 |
2024-01-26 | New perspectives of Hall effects from first-principles calculations | The Hall effect has been a fascinating topic ever since its discovery,
resulting in exploration of entire family of this intriguing phenomena. As the
field of topology develops and novel materials emerge endlessly over the past
few decades, researchers have been passionately debating the origins of various
Hall effects. Differentiating between the ordinary Hall effect and
extraordinary transport properties, like the anomalous Hall effect, can be
quite challenging, especially in high-conductivity materials, including those
with topological origins. In this study, we conduct a systematic and
comprehensive analysis of Hall effects by combining the semiclassical Boltzmann
transport theory with first principles calculations within the relaxation time
approximation. We first highlight some striking similarities between the
ordinary Hall effect and certain anomalous Hall effects, such as nonlinear
dependency on magnetic field and potential sign reversal of the Hall
resistivity. We then demonstrate that the Hall resistivity can be scaled with
temperature and magnetic field as well, analogue to the Kohler's rule which
scales the longitudinal resistivity under the relaxation time approximation. We
then apply this Kohler's rule for Hall resistivity to two representative
materials: ZrSiS and PtTe$_2$ with reasonable agreement with experimental
measurement. Moreover, our methodology has been proven to be applicable to the
planar Hall effects of bismuth, of perfect agreements with experimental
observations. Our research on the scaling behavior of Hall resistivity
addresses a significant gap in this field and provides a comprehensive
framework for a deeper understanding of the Hall resistance family, and thus
has potential to propel the field forward and spark further investigations into
the fascinating world of Hall effects. | 2401.15150v1 |
2012-04-12 | Effect of crystallographic anisotropy on the resistance switching phenomenon in perovskites | Resistance switching effects in metal/perovskite contacts based on epitaxial
c-axis oriented Y-Ba-Cu-O (YBCO) thin films with different crystallographic
orientations have been studied. Three types of Ag/YBCO junctions with the
contact restricted to (i) c-axis direction, (ii) ab-plane direction, and (iii)
both were designed and fabricated, and their current-voltage characteristics
have been measured. The type (i) junctions exhibited conventional bipolar
resistance switching behavior, whereas in other two types the low-resistance
state was unsteady and their resistance quickly relaxed to the initial
high-resistance state. Physical mechanism based on the oxygen diffusion
scenario, explaining such behavior, is discussed. | 1204.2598v1 |
2013-04-07 | Characterization and simulation of resistive-MPGDs with resistive strip and layer topologies | The use of resistive technologies to MPGD detectors is taking advantage for
many new applications, including high rate and energetic particle flux
scenarios. The recent use of these technologies in large area detectors makes
necessary to understand and characterize the response of this type of detectors
in order to optimize or constrain the parameters used in its production,
material resistivity, strip width, or layer thickness. The values to be chosen
will depend on the environmental conditions in which the detector will be
placed, and the requirements in time resolution and gain, improving the
detector performance for each given application. We present two different
methods to calculate the propagation of charge diffusion through different
resistive topologies; one is based on a FEM of solving the telegraph equation
in our particular strip detector scheme, the other is based on a
semi-analytical approach of charge diffusion and is used to determine the
charge evolution in a resistive layer. | 1304.2057v1 |
2014-07-31 | Compact chromium oxide thin film resistors for use in nanoscale quantum circuits | We report on the electrical characterisation of a series of thin chromium
oxide films, grown by dc sputtering, to evaluate their suitability for use as
on-chip resistors in nanoelectronics. By increasing the level of oxygen doping,
the room-temperature sheet resistance of the chromium oxide films was varied
from 28$\Omega / \square$ to 32.6k$\Omega / \square$. The variation in
resistance with cooling to 4.2K in liquid helium was investigated; the sheet
resistance at 4.2K varied with composition from 65$\Omega / \square$ to above
20G$\Omega / \square$. All of the films measured displayed ohmic behaviour at
all measured temperatures. For on-chip devices for quantum phase-slip
measurements using niobium-silicon nanowires, interfaces between
niobium-silicon and chromium oxide are required. By characterising the
interface contact resistance, we found that a gold intermediate layer is
favourable: the specfic contact resistivity of chromium-oxide-to-gold
interfaces was 0.15 m$\Omega$cm$^2$, much lower than the value for direct
chromium-oxide to niobium-silicon interfaces, 65m$\Omega$cm$^2$. We conclude
that these chromium oxide films are suitable for use in nanoscale circuits as
high-value resistors, with resistivity tunable by oxygen content. | 1407.8467v1 |
2016-06-12 | Interlayer Resistance of Misoriented MoS2 | Interlayer misorientation in transition metal dichalcogenides alters the
interlayer distance, the electronic band structure, and the vibrational modes,
but, its effect on the interlayer resistance is not known. This work analyzes
the coherent interlayer resistance of misoriented 2H-MoS2 for low energy
electrons and holes as a function of the misorientation angle. The electronic
interlayer resistance monotonically increases with the supercell lattice
constant by several orders of magnitude similar to that of misoriented bilayer
graphene. The large hole coupling gives low interlayer hole resistance that
weakly depends on the misorientation angle. Interlayer rotation between an
n-type region and a p-type region will suppress the electron current with
little effect on the hole current. We estimate numerical bounds and explain the
results in terms of the orbital composition of the bands at high symmetry
points. Density functional theory calculations provide the interlayer coupling
used in both a tunneling Hamiltonian and a non-equilibrium Green function
calculation of the resistivity. | 1606.03682v1 |
2017-11-30 | Universal Scaling in Intrinsic Resistivity of Two-Dimensional Metal Borophene | Two-dimensional boron sheets (borophenes) have been successfully synthesized
in experiments and are expected to exhibit intriguing transport properties such
as the emergence of superconductivity and Dirac Fermions. However, quantitative
understanding of intrinsic electrical transport of borophene has not been
achieved. Here, we report a comprehensive first-principles study on
electron-phonon driven intrinsic electrical resistivity (\r{ho}) of emerging
borophene structures. We find that the resistivity is highly dependent on the
atomic structures and electron density of borophene. Low-temperature
resistivity of borophene \r{ho} exhibits a universal scaling behavior, which
increases rapidly with temperature T (\r{ho}~T^4), while \r{ho} increases
linearly for a large temperature window T > 100 K. It is observed that this
universal behavior of intrinsic resistivity is well described by
Bloch-Gr\"unesisen model. Different from graphene and conventional
three-dimensional metals, the intrinsic resistivity of borophenes can be easily
tuned by adjusting carrier densities while the Bloch-Gr\"unesisen temperature
is nearly fixed at ~100 K. Our work suggests monolayer boron can serve as an
intriguing platform for realizing high-tunable two-dimensional electronic
devices. | 1711.11186v1 |
2018-05-05 | Tetrahedral amorphous carbon resistive memories with graphene-based electrodes | Resistive-switching memories are alternative to Si-based ones, which face
scaling and high power consumption issues. Tetrahedral amorphous carbon (ta-C)
shows reversible, non-volatile resistive switching. Here we report polarity
independent ta-C resistive memory devices with graphene-based electrodes. Our
devices show ON/OFF resistance ratios$\sim$4x$10^5$, ten times higher than with
metal electrodes, with no increase in switching power, and low power
density$\sim$14$\mu$W/$\mu$m$^2$. We attribute this to a suppressed tunneling
current due to the low density of states of graphene near the Dirac point,
consistent with the current-voltage characteristics derived from a quantum
point contact model. Our devices also have multiple resistive states. This
allows storing more than one bit per cell. This can be exploited in a range of
signal processing/computing-type operations, such as implementing logic,
providing synaptic and neuron-like mimics, and performing analogue signal
processing in non-von-Neumann architectures | 1805.02100v1 |
2017-03-10 | Unipolar resistive switching in cobalt titanate thin films | We report giant resistive switching of an order of 104, long-time charge
retention characteristics up to 104 s, non-overlapping SET and RESET voltages,
ohmic in low resistance state (LRS) and space charge limited current (SCLC)
mechanism in high resistance state (HRS) properties in polycrystalline
perovskite Cobalt Titanate (CoTiO3 ~ CTO) thin films. Impedance spectroscopy
study was carried out for both LRS and HRS states which illustrates that only
bulk resistance changes after resistance switching, however, there is a small
change (<10% which is in pF range) in the bulk capacitance value in both
states. These results suggest that in LRS state current filaments break the
capacitor in many small capacitors in a parallel configuration which in turn
provides the same capacitance in both states even there was 90 degree changes
in phase-angle and an order of change in the tangent loss. | 1703.03662v1 |
2015-04-21 | The question of intrinsic origin of the metal-insulator transition in i-AlPdRe quasicrystal | The icosahedral (i-) AlPdRe is the most resistive quasicrystalline alloy
discovered so far. Resistivities ($\rho$) of $1\Omega cm$ at 4K and correlated
resistance ratios ($RRR = \rho_{4K}/\rho_{300K}$) of more than 200 are observed
in polycrystalline samples. These values are two orders of magnitude larger
than for the isomorphous i-AlPdMn phase. We discuss here the controversial
microscopic origin of the i-AlPdRe alloy electrical specificity. It has been
proposed that the high resistivity values are due to extrinsic parameters, such
as secondary phases or oxygen contamination. From comprehensive measurements
and data from the literature including electronic transport correlated with
micro structural and micro chemical analysis, we show that on the contrary
there is mounting evidence in support of an origin intrinsic to the i-phase.
Similarly to the other quasicrystalline alloys, the electrical resistivity of
the i-AlPdRe samples depends critically on minute changes in the structural
quality and chemical composition. The low resistivity in i-AlPdRe single-grains
compared to polycrystaline samples can be explained by difference in chemical
composition, heterogeneity and thermal treatment. | 1504.05464v1 |
2023-04-08 | Novel resistive charge-multipliers for dual-phase LAr-TPCs: towards stable operation at higher gains | Cryogenic versions of Resistive WELL (RWELL) and Resistive Plate WELL
(RPWELL) detectors have been developed, aimed at stable avalanche
multiplication of ionization electrons in dual-phase TPCs. In the RWELL, a thin
resistive layer deposited on top of an insulator is inserted in between the
electron multiplier (THGEM) and the readout anode; in the RPWELL, a resistive
plate is directly coupled to the THGEM. Radiation-induced ionization electrons
in the liquid are extracted into the gaseous phase. They drift into the THGEM's
holes where they undergo charge multiplication. Embedding resistive materials
into the multiplier proved to enhance operation stability due to the mitigation
of electrical discharges - thus allowing operation at higher charge gain
compared to standard THGEM (a.k.a. LEM) multipliers. We present the detector
concepts and report on the main preliminary results. | 2304.04044v4 |
2012-02-10 | What Causes High Resistivity in CdTe | CdTe can be made semi-insulating by shallow donor doping. This is routinely
done to obtain high resistivity in CdTe-based radiation detectors. However, it
is widely believed that the high resistivity in CdTe is due to the Fermi level
pinning by native deep donors. The model based on shallow donor compensation of
native acceptors was dismissed based on the assumption that it is practically
impossible to control the shallow donor doping level so precisely that the free
carrier density can be brought below the desired value suitable for radiation
detection applications. In this paper, we present our calculations on carrier
statistics and energetics of shallow donors and native defects in CdTe. Our
results show that the shallow donor can be used to reliably obtain high
resistivity in CdTe. Since radiation detection applications require both high
resistivity and good carrier transport, one should generally use shallow donors
and shallow acceptors for carrier compensation and avoid deep centers that are
effective carrier traps. | 1202.2255v1 |
2003-05-17 | Saturation of electrical resistivity | Resistivity saturation is observed in many metallic systems with a large
resistivity, i.e., when the resistivity has reached a critical value, its
further increase with temperature is substantially reduced. This typically
happens when the apparent mean free path is comparable to the interatomic
separations - the Ioffe-Regel condition. Recently, several exceptions to this
rule have been found. Here, we review experimental results and early theories
of resistivity saturation. We then describe more recent theoretical work,
addressing cases both where the Ioffe-Regel condition is satisfied and where it
is violated. In particular we show how the (semiclassical) Ioffe-Regel
condition can be derived quantum-mechanically under certain assumptions about
the system and why these assumptions are violated for high-Tc cuprates and
alkali-doped fullerides. | 0305412v1 |
2004-07-06 | High pressure effects on the electrical resistivity behavior of the Kondo lattice, YbPd2Si2 | We report the influence of external pressure (P= up to 8 GPa) on the
temperature dependence of electrical resistivity of a Yb-based Kondo lattice,
YbPd2Si2, which does not undergo magnetic ordering under ambient pressure
condition. There are qualitative changes in the temperature dependence of
electrical resistivity due to the application of external pressure. While the
resistivity is found to vary quadratically below 15 K (down to 45 mK)
characteristic of Fermi-liquids, a drop is observed below 0.5 K for P= 1 GPa.
Since the resistance values do not attain zero, we are attempted to attribute
this drop to magnetic ordering, rather than to superconductivity. The
temperature at which this fall occurs goes through a peak as a function of P (8
K for2 GPa and about 5 K at higher pressures). mimicking Doniach's magnetic
phase diagram. We conclude that this is one of the few Yb-based stoichiometric
materials, in which one can travers from valence fluctuation to magnetic
ordering by the application of external pressure. | 0407125v1 |
2014-08-19 | Effect of silicon resistivity on its porosification using metal induced chemical etching | A comparison of porous structures formed from silicon (Si) wafers with
different resistivities has been reported here based on the morphological
studies carried out using scanning electron microscope (SEM). The porous Si
samples have been prepared using metal induced etching (MIE) technique from two
different Si wafers having two different resistivities. It is observed that
porous Si containing well aligned Si nanowires are formed from high resistivity
(1-20 $\Omega$cm) Si wafer whereas interconnected pores or cheese like
structures are formed from low resistivity (0.02 $\Omega$cm ) Si wafers after
MIE. An explanation for the different porosification processes has also been
proposed based on the initial doping level where number of dopants seems to be
playing an important role on the etching process. Visible photoluminescence
have been observed from all the porous samples possibly due to quantum
confinement effect. | 1408.4314v1 |
2020-09-07 | Tuneable Magneto-Resistance by Severe Plastic Deformation | Bulk metallic samples were synthesized from different binary powder mixtures
consisting of elemental Cu, Co, and Fe using severe plastic deformation. Small
particles of the ferromagnetic phase originate in the conductive Cu phase,
either by incomplete dissolution or by segregation phenomena during the
deformation process. These small particles are known to give rise to granular
giant magnetoresistance. Taking advantage of the simple production process, it
is possible to perform a systematic study on the influence of processing
parameters and material compositions on the magneto-resistance. Furthermore, it
is feasible to tune the magnetoresistive behavior as a function of the
specimens chemical composition. It was found that specimens of low
ferromagnetic content show an almost isotropic drop in resistance in a magnetic
field. With increasing ferromagnetic content, percolating ferromagnetic phases
cause an anisotropy of the magnetoresistance. By changing the parameters of the
high pressure torsion process, i.e., sample size, deformation temperature, and
strain rate, it is possible to tailor the magnitude of giant
magneto-resistance. A decrease in room temperature resistivity of approx. 3.5%
was found for a bulk specimen containing an approximately equiatomic fraction
of Co and Cu. | 2009.02952v1 |
2017-11-22 | High Efficiency Thin Film Superlattice Thermoelectric Cooler Modules Enabled by Low Resistivity Contacts | V-telluride superlattice thin films have shown promising performance for
on-chip cooling devices. Recent experimental studies have indicated that device
performance is limited by the metal/semiconductor electrical contacts. One
challenge in realizing a low resistivity contacts is the absence of fundamental
knowledge of the physical and chemical properties of interfaces between metal
and V-telluride materials. Here we present a combination of experimental and
theoretical efforts to understand, design and harness low resistivity contacts
to V-tellurides. Ab initio calculations are used to explore the effects of
interfacial structure and chemical compositions on the electrical contacts, and
an ab initio based macroscopic model is employed to predict the fundamental
limit of contact resistivity as a function of both carrier concentration and
temperature. Under the guidance of theoretical studies, we develop an
experimental approach to fabricate low resistivity metal contacts to
V-telluride thin film superlattices, achieving a 100-fold reduction compared to
previous work. Interfacial characterization and analysis using both scanning
transmission electron microscopy and energy-dispersive x-ray spectroscopy show
the unusual interfacial morphology and the potential for further improvement in
contact resistivity. Finally, we harness the improved contacts to realize an
improved high-performance thermoelectric cooling module. | 1711.08481v1 |
2000-02-17 | Ion-Beam Induced Current in High-Resistance Materials | The peculiarities of electric current in high-resistance materials, such as
semiconductors or semimetals, irradiated by ion beams are considered. It is
shown that after ion--beam irradiation an unusual electric current may arise
directed against the applied voltage. Such a negative current is a transient
effect appearing at the initial stage of the process. The possibility of using
this effect for studying the characteristics of irradiated materials is
discussed. A new method for defining the mean projected range of ions is
suggested. | 0002264v1 |
2021-11-15 | Resistive-nanoindentation on gold: Experiments and modeling of the electrical contact resistance | This paper reports the experimental, analytical, and numerical study of
resistive-nanoindentation tests performed on gold samples (bulk and thin film).
First, the relevant contributions to electrical contact resistance are
discussed and analytically described. A brief comparison of tests performed on
gold and on natively oxidized metals highlights the high reproducibility and
the voltage-independence of experiments on gold(thanks to its oxide-free
surface). Then, the evolution of contact resistance during nanoindentation is
fully explained in terms of electronic transport regimes: starting from
tunneling, electronic transport is then driven by ballistic conduction before
ending with pure diffusive conduction. The corresponding analytical
expressions, as well as their validity domains, are determined and compared
with experimental data,showing excellent agreement. From there, focus is made
on the diffusive regime. Resistive-nanoindentation outputs are fully described
by analytical and finite-element modeling. The developed numerical framework
allows a better understanding of the main parameters: it first assesses the
technique capabilities (validity domains, sensitivity to tip defect,
sensitivity to rheology, effect of an oxide layer, and so on), butit also
validates the different assumptions made on current line distribution. Finally,
it is shown that a simple calibration procedure allows a well-resolved
monitoring of the contact area during resistive-nanoindentation performed on
samples with complex rheologies (ductile thin film on an elastic substrate).
Comparison to analytical and numerical approaches highlights the strength of
resistive-nanoindentation for continuous area monitoring. | 2111.15474v1 |
2023-08-09 | Observation of abnormal resistance-temperature behavior along with diamagnetic transition in Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O-based composite | Recently, Sukbae Lee et al.reported that material
Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O (LK-99) has a series of characteristics of room
temperature superconductors, including diamagnetic transition, resistance jump,
nearly zero-resistance, magnetic field-dependent IV characteristics and so on
(10.6111/JKCGCT.2023.33.2.061, arXiv:2307.12008, arXiv:2307.12037). However,
whether LK-99 is really a room temperature superconductor is still
controversial. On the one hand, some people think that the relatively weak
diamagnetism of LK-99 reported by Sukbae Lee et al. is not the Meissner effect.
On the other hand, there are doubts about the authenticity of its
zero-resistance test results. Global replication studies have shown that LK-99
does have a large diamagnetic (arXiv:2308.01516), and also found a
zero-resistance behavior at a low temperature of 110 $^\circ$K
(arXiv:2308.01192). However, up to now, there is still no direct reproducible
evidence to support Sukbae Lee et al.'s conclusion that LK-99 is a room
temperature superconductor. Here, a distinct resistance jump was observed at
about 387 $^\circ$K under ambient pressure in our experiment for unclear reason
including possible impurity's contribution. The overall resistance of the test
LK-99 sample still shows semiconductivity, and the resistance cannot really
drop to zero. Our findings indicate that to identify the true potential of
LK-99, high quality crystals without impurity are very important. | 2308.05001v1 |
1995-12-14 | Vortex structure and resistive transitions in high-Tc superconductors | The nature of the resistive transition for a current applied parallel to the
magnetic field in high-Tc materials is investigated by numerical simulation on
the three dimensional Josephson junction array model. It is shown by using
finite size scaling that for samples with disorder the critical temperature Tp
for the c axis resistivity corresponds to a percolation phase transition of
vortex lines perpendicularly to the applied field. The value of Tp is higher
than the critical temperature for j perpendicular to H, but decreases with the
thickness of the sample and with anisotropy. We predict that critical behavior
around Tp should reflect in experimentally accessible quantities, as the I-V
curves. | 9512003v1 |
2010-06-26 | Stabilizing the forming process in unipolar resistance switching using an improved compliance current limiter | The high reset current IR in unipolar resistance switching now poses major
obstacles to practical applications in memory devices. In particular, the first
IR-value after the forming process is so high that the capacitors sometimes do
not exhibit reliable unipolar resistance switching. We found that the
compliance current Icomp is a critical parameter for reducing IR-values. We
therefore introduced an improved, simple, easy to use Icomp-limiter that
stabilizes the forming process by drastically decreasing current overflow, in
order to precisely control the Icomp- and subsequent IR-values. | 1006.5132v1 |
2011-07-06 | Hysteretic magnetic pinning and reversible resistance switching in High-Tc superconductor/ferromagnet multilayers | We study a high-TC superconducting (YBa2Cu3O7-d) / ferromagnetic (Co/Pt
multilayer) hybrid which exhibits resistance switching driven by the magnetic
history: depending on the direction of the external field, a pronounced
decrease or increase of the mixed-state resistance is observed as magnetization
reversal occurs within the Co/Pt multilayer. We demonstrate that stray magnetic
fields cause these effects via i) creation of vortices/antivortices and ii)
magnetostatic pinning of vortices that are induced by the external field. | 1107.1122v1 |
2017-05-11 | The role of contact resistance in graphene field-effect devices | The extremely high carrier mobility and the unique band structure, make
graphene very useful for field-effect transistor applications. According to
several works, the primary limitation to graphene based transistor performance
is not related to the material quality, but to extrinsic factors that affect
the electronic transport properties. One of the most important parasitic
element is the contact resistance appearing between graphene and the metal
electrodes functioning as the source and the drain. Ohmic contacts to graphene,
with low contact resistances, are necessary for injection and extraction of
majority charge carriers to prevent transistor parameter fluctuations caused by
variations of the contact resistance. The International Technology Roadmap for
Semiconductors, toward integration and down-scaling of graphene electronic
devices, identifies as a challenge the development of a CMOS compatible process
that enables reproducible formation of low contact resistance. However, the
contact resistance is still not well understood despite it is a crucial barrier
towards further improvements. In this paper, we review the experimental and
theoretical activity that in the last decade has been focusing on the reduction
of the contact resistance in graphene transistors. We will summarize the
specific properties of graphene-metal contacts with particular attention to the
nature of metals, impact of fabrication process, Fermi level pinning, interface
modifications induced through surface processes, charge transport mechanism,
and edge contact formation. | 1705.04025v1 |
2022-09-13 | Unconventional Resistivity Scaling in Topological Semimetal CoSi | Nontrivial band topologies in semimetals lead to robust surface states that
can contribute dominantly to the total conduction. This may result in reduced
resistivity with decreasing feature size contrary to conventional metals, which
may highly impact the semiconductor industry. Here we study the resistivity
scaling of a representative topological semimetal CoSi using realistic band
structures and Green's function methods. We show that there exists a critical
thickness d_c dividing different scaling trends. Above d_c, when the defect
density is low such that surface conduction dominates, resistivity reduces with
decreasing thickness; when the defect density is high such that bulk conduction
dominates, resistivity increases in as conventional metals. Below d_c, the
persistent remnants of the surface states give rise to decreasing resistivity
down to the ultrathin limit, unlike in topological insulators. The observed
CoSi scaling can apply to broad classes of topological semimetals, providing
guidelines for materials screening and engineering. Our study shows that
topological semimetals bear the potential of overcoming the resistivity scaling
challenges in back-end-of-line interconnect applications. | 2209.06135v1 |
2019-10-31 | Tackling Challenges in Seebeck Coefficient Measurement of Ultra-High Resistance Samples with an AC Technique | Seebeck coefficient is a widely-studied semiconductor property. Conventional
Seebeck coefficient measurements are based on DC voltage measurement. Normally
this is performed on samples with low resistances below a few Mohm level.
Meanwhile, certain semiconductors are highly intrinsic and resistive, many
examples can be found in optical and photovoltaic materials. The hybrid halide
perovskites that have gained extensive attention recently are a good example.
Few credible studies exist on the Seebeck coefficient of, CH3NH3PbI3, for
example. We report here an AC technique based Seebeck coefficient measurement,
which makes high quality voltage measurement on samples with resistances up to
100Gohm. This is achieved through a specifically designed setup to enhance
sample isolation and reduce meter loading. As a demonstration, we performed
Seebeck coefficient measurement of a CH3NH3PbI3 thin film at dark and found S =
+550 microV/K. Such property of this material has not been successfully studied
before. | 1910.14205v1 |
2021-04-03 | Resistive switching of tetraindolyl derivative in ultrathin films: A potential candidate for non-volatile memory applications | Bipolar resistive switching using organic molecule is very promising for
memory application owing to their advantages like simple device structure, low
manufacturing cost, their stability and flexibility etc. Herein we report
Langmuir-Blodgett and spin-coated film based bipolar resistive switching
devices using organic material indole derivative. Pressure - area per molecule
isotherm, Brewster Angle Microscopy, Atomic Force Microscopy and Scanning
Electron Microscopy were used to have an idea about organization and morphology
of the organic material onto thin film. Based on device structure and
measurement protocol it is observed that the device made up of 1 shows
non-volatile Resistive Random Access Memory behaviour with very high memory
window, data sustainability and repeatability.Oxidation-reduction process as
well as electric field driven conduction are the key behind such switching
behaviour.Due to very good data retention, repeatability, stability and high
device yield the switching device designed using compound 1may be a potential
candidate for memory applications. | 2104.01298v1 |