publicationDate stringlengths 10 10 | title stringlengths 17 233 | abstract stringlengths 20 3.22k | id stringlengths 9 12 |
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2012-09-26 | Effect of rotation of the polarization of linearly polarized microwaves on the radiation-induced magnetoresistance oscillations | Light-matter coupling is investigated by rotating, by an angle \theta, the
polarization of linearly polarized microwaves with respect to the long-axis of
GaAs/AlGaAs Hall-bar electron devices. At low microwave power, P, experiments
show a strong sinusoidal variation in the diagonal resistance R_{xx} vs. \theta
at the oscillatory extrema, indicating a linear polarization sensitivity in the
microwave radiation-induced magnetoresistance oscillations. Surprisingly, the
phase shift \theta_{0} for maximal oscillatory R_{xx} response under
photoexcitation appears dependent upon the radiation-frequency f, the extremum
in question, and the magnetic field orientation or sgn(B). | 1209.5808v1 |
2012-09-27 | Interaction effects and transport properties of Pt capped Co nanoparticles | We studied the magnetic and transport properties of Co nanoparticles (NPs)
being capped with varying amounts of Pt. Beside field and temperature dependent
magnetization measurements we performed delta-M measurements to study the
magnetic interactions between the Co NPs. We observe a transition from
demagnetizing towards magnetizing interactions between the particles for an
increasing amount of Pt capping. Resistivity measurements show a crossover from
giant magnetoresistance towards anisotropic magnetoresistance. | 1209.6255v1 |
2012-10-18 | Possibility of Exciton Mediated Superconductivity in Nano-Sized Sn/Si Core-Shell Clusters: A Process Technology towards Heterogeneous Material in Nano-Scale | We have produced Sn/Si core-shell cluster assemblies by a
plasma-gas-condensation cluster beam deposition apparatus. For the sample with
Si content = 12 at.%, the temperature dependence of electrical resistivity
exhibits a metallic behavior above 10K and the onset of superconducting
transition below 6.1 K. With decreasing temperature, the thermomagnetic curve
for the sample with Si content = 8 at.% begins to decrease steadily toward
negative value below 7.7 K, indicating the Meissner effect. An increase in the
transition temperature, TC is attributable to exciton-typesuperconductivity. | 1210.5027v1 |
2012-10-29 | Optical Absorption Measurements on Crystalline Silicon at 1550nm | Crystalline silicon is currently being discussed as test-mass material for
future generations of gravitational wave detectors that will operate at
cryogenic temperatures. We present optical absorption measurements on a
large-dimension sample of crystalline silicon at a wavelength of 1550nm at room
temperature. The absorption was measured in a monolithic cavity setup using the
photo-thermal self-phase modulation technique. The result for the absorption
coefficient of this float-zone sample with a specific resistivity of 11kOhm cm
was measured to be \alpha_A=(264 +/- 39)ppm/cm. | 1210.7763v2 |
2012-12-17 | Anomalous Hall Effect in perpendicularly magnetized Mn(_{3-x})Ga thin films | Mn$_{3-x}$Ga (x = 0.1, 0.4, 0.7) thin films on MgO and SrTiO$_3$ substrates
were investigated with magnetic anisotropy perpendicular to the film plane. An
anomalous Hall-effect was observed for the tetragonal distorted lattice in the
crystallographic D0$_{22}$ phase. The Hall resistivity $\varrho_{xy}$ was
measured in a temperature range from 20 to 330 K. The determined skew
scattering and side jump coefficients are discussed with regard to the film
composition and used substrate and compared to the crystallographic and
magnetic properties. | 1212.4019v1 |
2013-03-07 | Thickness dependence of the degree of spin polarization of the electrical current in permalloy thin films | Spin-polarized electrical transport is investigated in $
Al_{2}O_{3}/Ni_{80}Fe_{20}/Al_{2}O_{3}$ thin films for permalloy thickness
between 6 and 20nm. The degree of spin-polarization of the current flowing in
the plane of the film is measured through the current induced spin wave Doppler
shift. We find that it decreases as the film thickness decreases, from 0.72 at
20nm to 0.46 at 6nm. This decrease is attributed to a spin depolarization
induced by the film surfaces. A model is proposed which takes into account the
contributions of the different sources of electron scattering (alloy disorder,
phonons, thermal magnons, grain boundaries, film surfaces) to the measured
spin-dependent resistivities. | 1303.1692v1 |
2013-06-12 | Electron transport across a metal-organic interface | We simulate the electron transport across the Au(111)-pentacene interface
using non-equilibrium Green's functions and density-functional theory
(NEGF-DFT), and calculate the bias-dependent electron transmission. We find
that the electrical contact resistance is dominated by the formation of a
Schottky barrier at the interface, and show that the conventional semiconductor
transport models across Schottky barriers need to be modified in order to
describe the simulation data. We present an extension of the conventional
Schottky barrier transport model, which can describe our simulation results and
rationalize recent experimental data. | 1306.2731v1 |
2013-06-26 | A singularly perturbed non-ideal transmission problem and application to the effective conductivity of a periodic composite | We investigate the effective thermal conductivity of a two-phase composite
with thermal resistance at the interface. The composite is obtained by
introducing into an infinite homogeneous matrix a periodic set of inclusions of
a different material. The diameter of each inclusion is assumed to be
proportional to a positive real parameter \epsilon. Under suitable assumptions,
we show that the effective conductivity can be continued real analytically in
the parameter \epsilon around the degenerate value \epsilon=0, in
correspondence of which the inclusions collapse to points. | 1306.6176v1 |
2013-07-12 | Observation of Longitudinal Spin Seebeck Effect with Various Transition Metal Films | We evaluated the thermoelectric properties of longitudinal spin Seebeck
devices by using ten different transition metals (TMs). Both the intensity and
sign of spin Seebeck coefficients were noticeably dependent on the degree of
the inverse spin Hall effect and the resistivity of each TM film. Spin
dependent behaviors were also observed under ferromagnetic resonance. These
results indicate that the output of the spin Seebeck devices originates in the
spin current. | 1307.3320v1 |
2013-08-08 | Planar Superconducting Whispering Gallery Mode Resonators | We introduce a microwave circuit architecture for quantum signal processing
combining design principles borrowed from high-Q 3D resonators in the quantum
regime and from planar structures fabricated with standard lithography. The
resulting '2.5D' whispering-gallery mode resonators store 98% of their energy
in vacuum. We have measured internal quality factors above 3 million at the
single photon level and have used the device as a materials characterization
platform to place an upper bound on the surface resistance of thin film
aluminum of less than 250nOhms. | 1308.1743v2 |
2013-09-02 | Model of the Electrostatics and Tunneling Current of Metal-Graphene Junctions and Metal-Insulator-Graphene Heterostructures | In this paper we present a comprehensive model for the tunneling current of
the metal-insulator-graphene heterostructure, based on the Bardeen Transfer
Hamiltonian method, of the metal-insulator-graphene heterostructure. As a
particular case we have studied the metal-graphene junction, unveiling the role
played by different electrical and physical parameters in determining the
differential contact resistance. | 1309.0390v1 |
2013-09-19 | Giant electroresistance and tunable magnetoelectricity in a multiferroic junction | First-principles density functional calculations show that the
$\textrm{SrRuO}_{3}/\textrm{PbTiO}_{3}/\textrm{SrRuO}_{3}$ multiferroic
junction with asymmetric (RuO$_{2}$/PbO and TiO$_{2}$/SrO) interfaces has a
large ferroelectric depolarizing field, whose switching changes the interface
transmission probabilities for tunneling electrons, leading to
electroresistance modulation over several orders of magnitude. The switching
further affects the interface spin density, naturally driving magnetoresistance
as well as modulated spin-dependent in-plane resistivity, which may be
exploited in field-effect devices. | 1309.4883v2 |
2013-11-28 | Gate controlled spin pumping at a quantum spin Hall edge | We propose a four-terminal device designed to manipulate by all electrical
means the spin of a magnetic adatom positioned at the edge of a quantum spin
Hall insulator. We show that an electrical gate, able to tune the interface
resistance between a quantum spin Hall insulator and the source and drain
electrodes, can switch the device between two regimes: one where the system
exhibits spin pumping and the other where the adatom remains in its ground
state. This demonstrates an all-electrical route to control single spins by
exploiting helical edge states of topological materials. | 1311.7329v1 |
2014-03-02 | Spin disorder in an Ising honeycomb chain cobaltate | We report on a member of the spin-disordered honeycomb lattice
antiferromagnet in a quasi-one-dimensional cobaltate Ba_3Co_2O_6(CO_3)_0.7.
Resistivity exhibits as semimetallic along the face-sharing CoO6 chains.
Magnetic susceptibility shows strongly anisotropic Ising-spin character with
the easy axis along the chain due to significant spin-orbit coupling and a
trigonal crystal field. Nevertheless, ^135Ba NMR detects no indication of the
long-range magnetic order down to 0.48 K. Marginally itinerant electrons
possess large entropy and low-lying excitations with a Wilson ratio R_W = 116,
which highlight interplays of charge, spin, and orbital in the disordered
ground state. | 1403.0208v1 |
2014-03-18 | Quantum longitudinal and Hall transport at the LaAlO3/SrTiO3 interface at low electron densities | We examined the magneto-transport behavior of electrons confined at the
conducting LaAlO3/SrTiO3 interface in the low sheet carrier density regime. We
observed well resolved Shubnikov-de Haas quantum oscillations in the
longitudinal resistance, and a plateau-like structure in the Hall conductivity.
The Landau indices of the plateaus in the Hall conductivity data show spacing
close to 4, in units of the quantum of conductance. These experimental features
can be explained by a magnetic breakdown transition, which quantitatively
explains the area, structure, and degeneracy of the measured Fermi surface. | 1403.4343v1 |
2014-03-18 | 31P NMR Investigation of the Superconductor LiFeP (Tc = 5 K) | We investigate the static and dynamic spin susceptibility of the 111 type
Fe-based superconductor LiFeP with Tc ~ 5 K through the measurement of Knight
shift 31K and the spin-lattice relaxation rate 1/T1 at 31P site by nuclear
magnetic resonance. The constant 31K, small magnitudes of 1/T1T, along with the
resistivity rho ~ T^2 all point to the weak spin correlations in LiFeP. 1/T1T
display small enhancement toward Tc, indicating that the superconductivity is
intimately correlated with the antiferromagnetic spin fluctuations. | 1403.4458v1 |
2014-03-21 | Field induced large magnetocaloric effect and magnetoresistance in ErNiSi | Large magnetocaloric effect (MCE) and magnetoresistance (MR) together with
negligible hysteresis loss has been observed in ErNiSi compound, which
undergoes metamagnetic transition at low temperatures. Magnetization, heat
capacity and resistivity measurements confirm the metamagnetic transition. The
maximum value of isothermal entropy change and MR for a field change of 50 kOe
are found to be 19.1 J/kg K and -34 %. Large MCE with negligible magnetic
hysteresis loss could make this material promising for low temperature magnetic
refrigeration. | 1403.5396v1 |
2014-06-17 | Phenomenological Modeling of Memristive Devices | We present a computationally inexpensive yet accurate phenomenological model
of memristive behavior in titanium dioxide devices by fitting experimental
data. By design, the model predicts most accurately I-V relation at small
non-disturbing electrical stresses, which is often the most critical range of
operation for circuit modeling. While the choice of fitting functions is
motivated by the switching and conduction mechanisms of particular titanium
dioxide devices, the proposed modeling methodology is general enough to be
applied to different types of memory devices which feature smooth non-abrupt
resistance switching. | 1406.4219v2 |
2014-12-21 | A brief introduction to giant magnetoresistance | Giant magnetoresistance (GMR) is a quantum mechanical magnetoresistance
effect observed in thin film structures composed of alternating ferromagnetic
and nonmagnetic layers. The effect manifests itself as a significant decrease
(typically 10-80%) in electrical resistance in the presence of a magnetic
field. The effect is exploited commercially by manufacturers of hard disk
drives. The 2007 Nobel Prize in physics was awarded to Albert Fert and Peter
Grunberg for the discovery of GMR. | 1412.7691v1 |
2015-02-10 | Preventing Buckling of Slender Cylindrical Structures by Internal Viscous Flows | Viscous flows within an elastic structure apply stress on the solid-liquid
interface. The stress-field created by the viscous flow can be utilized to
counter stress created by external forces and thus may be applied as a tool for
delaying the onset of structural failure. To illustrate this concept we study
viscous flow within an elastic cylinder under compressive axial force. We
obtain a closed-form expression showing an approximately linear relation
between the critical buckling load and the liquid inlet pressure. Our results
are validated by numerical computations. We discuss future research directions
of fluid-solid composite materials which create flow under external stress,
yielding enhanced resistance to structural failure. | 1502.02814v1 |
2015-03-04 | Adiabatic Joule Heating of Copper from 4 K to the Melting Temperature | Considering a copper wire heated by Joule effect and the variation of its
resistivity and specific heat with temperature, we established numerical and
analytical solutions (between 293 and 1356 K for the latter) for the evolution
of its temperature over time. The Temperature vs. Time evolution follows a
Lambertian function. The calculations are based on the assumption of adiabatic
heating and uniform current distribution within the wire. We demonstrate that
at very low temperature the heating rate is strongly dependent on copper
purity. | 1503.01279v1 |
2015-08-17 | Evidence for resonant scattering of electrons by spin fluctuations in $LaNiO_3/LaAlO_3$ heterostructures grown by pulsed laser deposition | We present measurements of resistivity $\rho$ in highly oriented $LaNiO_3$
films grown on $LaAlO_3$ substrates by using a pulsed laser deposition
technique. The experimental data are found to follow a universal $\rho (T)
\propto T^{3/2}$ dependence for the entire temperature interval ($20K<T<300K$).
The observed behavior has been attributed to a resonant scattering of electrons
on antiferromagnetic fluctuations (with a characteristic energy $\hbar \omega
_{sf}\simeq 2.1meV$) triggered by spin-density wave propagating through the
interface boundary of $LaNiO_3/LaAlO_3$ sandwich. | 1508.04063v1 |
2015-09-14 | Multi-Fields Modulation of Physical Properties of Oxide Thin Films | Oxide thin films exhibit versatile physical properties such as magnetism,
ferroelectricity, piezoelectricity, metal-insulator transition (MIT),
multiferroicity, colossal magnetoresistivity, switchable resistivity, etc. More
importantly, the exhibited multifunctionality could be tuned by various
external fields, which has enabled demonstration of novel electronic devices.
In this article, recent studies of the multi-fields modulation of physical
properties in oxide thin films have been reviewed. Some of the key issues and
prospects about this field are also addressed. | 1509.03939v1 |
2015-11-24 | Structural Properties and Thermodynamics of Hafnium sub-oxides in RRAM | We study the structural and electronic properties of various hafnium
sub-oxides HfzO from z = 9 to z = 0.5, by ab initio simulation using Density
Functional Theory. The stability of these sub-oxides is studied against
monoclinic HfO2. The progressive oxidation of a given HfzO is also envisaged
toward stoichiometric HfO2. The analogy with a conductive region of electrons
inside a HfO2 matrix is discussed within the context of Oxide-based Resistive
Random Access Memories (OxRRAM) devices which employ hafnium dioxide as an
insulator. | 1511.07665v1 |
2016-01-01 | Reverse degradation of nickel graphene junction by hydrogen annealing | Metal contacts are fundamental building components for graphene based
electronic devices and their properties are greatly influenced by interface
quality during device fabrication, leading to resistance variation. Here we
show that nickel graphene junction degrades after air exposure, due to
interfacial oxidation, thus creating a tunneling barrier. Most importantly, we
demonstrate that hydrogen annealing at moderate temperature (300 0C) is an
effective technique to reverse the degradation. | 1601.00109v2 |
2016-01-06 | Electronic transport through a silicene-based zigzag and armchair junction | Using density functional theory and non-equilibrium Greens function
technique, we performed theoretical investigations on the transport properties
of several ZAZ SiNRs junctions,a similar kind of silicene molecules junction
combined by zigzag and armchair silicene nanoribbons. It is found that the
differential conductances of the three systems decrease with an order of
5-ZAZ>4-ZAZ>3-ZAZ.Particularly,the Negative differential resistance can be
observed within certain bias voltage range only in 3-ZAZ SiNRs. In order to
elucidate the mechanism the NDR behavior, the transmission spectra and
molecular projected selfconsistent Hamiltonian states are discussed in details. | 1601.01066v1 |
2016-01-18 | Investigation of ITO based liquid sensor for ammonia hydroxide detection | We proposed an Indium Tin Oxide (ITO) sensor for detecting the NH4OH in
seawater and carried out a series of experiments to investigate the feasibility
of it as a hazardous and noxious substance (HNS) sensor. The ITO layer revealed
a distinct resistance change ({\delta}R) which is linearly correlated with the
NH4OH concentration. Sensing mechanism of the porous ITO layer has been
explained in terms of reduction and electrical double layer (EDL) formation.
Also, the chemical stability of ITO as a HNS sensor has verified. | 1601.04446v1 |
2016-01-18 | Low temperature phase diagram of hydrogen at pressures up to 380 GPa. A possible metallic phase at 360 GPa and 200 K | Two new phases of hydrogen have been discovered at room temperature in Ref.1:
phase IV above 220 GPa and phase V above ~270 GPa. In the present work we have
found a new phase VI at P~360 GPa and T<200 K. This phase is likely metallic as
follows from the featureless Raman spectra, a strong drop in resistance, and
absence of a photoconductive response. We studied hydrogen at low temperatures
with the aid of Raman, infrared absorption, and electrical measurements at
pressures up to 380 GPa, and have built a new phase diagram of hydrogen. | 1601.04479v1 |
2016-05-17 | Insulator to metal transition of WO3 epitaxial films induced by electrochemical Li-ion intercalation | We investigated systematic evolutions of structural and electronic properties
of LixWO3 films, induced by Li-ion electrochemical reactions.
Chronoamperometric Li-ion intercalation could control the amount of Li content
up to x ~ 0.5. The resistivity abruptly decreased with increasing x and the
films underwent an insulator to metal transition (IMT) within a range of 0.2 <
x < 0.24, which was consistent with IMT of cubic NaxWO3. The X-ray diffraction
analyses revealed the coexistence of tetragonal and cubic phases across IMT,
suggesting that the alkaline-ion content was a primary factor for metallic
conductivity in the ReO3-type WO3 system. | 1605.04997v1 |
2016-07-19 | Specific Heat and Electrical Transport Properties of Sn0.8Ag0.2Te Superconductor | Sn0.8Ag0.2Te is a new superconductor with Tc ~ 2.4 K. The superconducting
properties of Sn0.8Ag0.2Te have been investigated by specific heat measurements
under magnetic fields. Bulk nature of superconductivity was confirmed from the
amplitude of the specific heat jump at the superconducting transition, and the
amplitude is consistent with fully-gapped superconductivity. Upper critical
field was estimated from specific heat and electrical resistivity measurements
under magnetic fields. The Hall coefficient was positive, suggesting that the
Ag acts as a p-type dopant in Sn0.8Ag0.2Te. | 1607.05474v1 |
2016-10-21 | Electromotive forces generated in 3d-transition ferromagnetic metal films themselves under their ferromagnetic resonance | We report the electromotive force (EMF) properties generated in 3d-transition
ferromagnetic metal (FM = Fe, Co, and Ni80Fe20) films themselves under their
ferromagnetic resonance (FMR). For Fe and Co films, the EMF due to the
anomalous-Hall effect is dominantly generated under their FMR. Meanwhile, for a
Ni80Fe20 film, the EMF due to the inverse spin-Hall effect in the Ni80Fe20 film
itself under the FMR is mainly generated. This tendency is qualitatively
explained with differences of the spin polarization, the spin Hall
conductivity, the anomalous Hall conductivity, the magnetization saturation,
and the resistivity of the FM films. | 1610.06695v2 |
2016-11-27 | Probing Electron Spin Resonance in Monolayer Graphene | The precise value of the $g$-factor in graphene is of fundamental interest
for all spin-related properties and their application. We investigate monolayer
graphene on a Si/SiO2 substrate by resistively detected electron spin resonance
(ESR). Surprisingly, the magnetic moment and corresponding g-factor of
1.952+/-0.002 is insensitive to charge carrier type, concentration, and
mobility. | 1611.08782v1 |
2016-12-14 | Dielectric geometric phase optical elements from femtosecond direct laser writing | We propose to use femtosecond direct laser writing technique to realize
dielectric optical elements from photo-resist materials for the generation of
structured light from purely geometrical phase transformations. This is
illustrated by the fabrication and characterization of spin-to-orbital optical
angular momentum couplers generating optical vortices of topological charge
from 1 to 20. In addition, the technique is scalable and allows obtaining
microscopic to macroscopic flat optics. These results thus demonstrate that
direct 3D photopolymerization technology qualifies for the realization of
spin-controlled geometric phase optical elements. | 1612.04487v1 |
2016-12-06 | Development of an Experimental Setup to Analyze Carbon/Epoxy Composite Subjected to Current Impulses | In this paper, variation in electrical properties of CFRP caused by
relatively low magnitude current impulses discharged through CFRP coupons are
reported, and internal changes of the composite, due to current impulses, are
studied. Based on electrical resistance measurements caused by these currents,
property changes in CFRP composite coupons of two different carbon ply
orientations are compared. Furthermore, it will be investigated if the changes
caused by current impulses are mainly focused in the region of the current
injection at the edges of composite coupons, or are they distributed uniformly
through the bulk of the composite. | 1612.07204v1 |
2016-12-28 | Tomonaga-Luttinger liquid and localization in Weyl semimetals | We study both noncentrosymmetric and time-reversal breaking Weyl semimetal
systems under a strong magnetic field with the Coulomb interaction. The
three-dimensional bulk system is reduced to many mutually interacting
quasi-one-dimensional wires. Each strongly correlated wire can be approached
within the Tomonaga-Luttinger liquid formalism. Including impurity scatterings,
we inspect the localization effect and the temperature dependence of the
electrical resistivity. The effect of a large number of Weyl points in real
materials is also discussed. | 1612.08905v2 |
2018-03-22 | Vortex liquid phase in the p-wave ferromagnetic superconductor UCoGe | The upper critical field for field along the b-axis of the p-wave
ferromagnetic superconductor UCoGe has a particular S-shape, akin to the
re-entrant superconducting phase of URhGe. To explore the evolution of the
superconducting phase under this transverse magnetic field, we report the
thermal conductivity and resistivity measurements, revealing a possible
field-induced vortex liquid phase, and supporting a field-induced change of the
superconducting order parameter. | 1803.08468v3 |
2018-04-20 | Redox reaction enhanced Schottky contact at a \LNO{}(001)/Al interface | Emergent phenomena at interfaces between oxides and metals can appear due to
charge transfer and mass transport that modify the bulk properties. By coating
the metallic oxide LaNiO$_3$ by aluminium, we fabricated a junction exhibiting
a diode-like behaviour. At the equilibrium, the interface is insulating. The
metallic behaviour can be recovered by applying a voltage drop across the
junction in one polarity only. The electrical properties in direct and reverse
bias are investigated. The observed electro-resistive effect rises up to $10^5$
\% and can be interpreted in terms of (i) a spontaneous redox reaction
occurring at the interface and (ii) its reversal induced by charge injection in
direct bias. | 1804.07574v1 |
2018-06-13 | Vortex spin-valve on a topological insulator | Spin-valve structures are usually associated with the ability to modify the
resistance of electrical currents. We here demonstrate a profoundly different
effect of a spin-valve. In combination with a topological insulator and
superconducting materials, we show that a spin-valve can be used to toggle
quantum vortices in and out of existence. In the antiparallel configuration,
the spin-valve causes superconducting vortex nucleation. In the parallel
configuration, however, no vortices appear. This switching effect suggests a
new way to control quantum vortices. | 1806.05184v1 |
2018-09-25 | Anomalous Transport Behavior in Quantum Magnets | Transport behavior characterized by a low-temperature electrical resistivity
that displays a power-law behavior $\rho(T\to 0) \propto T^s$ with an exponent
$s<2$, is commonly observed in magnetic materials in both the magnetic and
nonmagnetic phases. We give a pedagogical overview of this phenomenon that
summarizes both the experimental situation and the state of its theoretical
understanding. We also put it in context by drawing parallels with unusual
power-law transport behavior in other systems. | 1809.09675v1 |
2018-09-28 | Magneto-dielectric and Magneto-resistive in the Mixed Spinel MgFe2O4 | The mixed spinel, MgFe2O4 has been synthesized by ball-milling assisted
sintering method. X-ray diffraction study confirms formation of cubic MgFe2O4
and the lattice parameter values calculated are a = b = c = 8.369(3) {\AA}.
Vibrating sample magnetometer measurements at room temperature shows a soft
ferrimagnetic nature. Magneto-Dielectric and Magneto-Restive plots confirm
coupling at room temperature in the prepared MgFe2O4. The peak at 500 Oe in the
MD plot is due to the canting of Fe3+ ions distributed in octahedral and
tetrahedral sites. | 1809.10968v1 |
2014-08-21 | Simulation of Schottky-Barrier Phosphorene Transistors | Schottky barrier field-effect transistors (SBFETs) based on few and mono
layer phosphorene are simulated by the non-equilibrium Green's function
formalism. It is shown that scaling down the gate oxide thickness results in
pronounced ambipolar I-V characteristics and significant increase of the
minimal leakage current. The problem of leakage is especially severe when the
gate insulator is thin and the number of layer is large, but can be effectively
suppressed by reducing phosphorene to mono or bilayer. Different from
two-dimensional graphene and layered dichalcogenide materials, both the
ON-current of the phosphorene SBFETs and the metal-semiconductor contact
resistance between metal and phosphorene strongly depend on the transport
crystalline direction. | 1408.5013v1 |
2004-06-10 | Magnetic and orbital blocking in Ni nanocontacts | We address the fundamental question of whether magneto-resistance (MR) of
atomic-sized contacts of Nickel is very large because of the formation of a
domain wall (DW) at the neck. Using {\em ab initio} transport calculations we
find that, as in the case of non-magnetic electrodes, transport in Ni
nanocontacts depends very much on the orbital nature of the electrons. Our
results are in agreement with several experiments in the average value of the
conductance. On the other hand, contrary to existing claims, DW scattering does
{\em not} account for large MR in Ni nanocontacts. | 0406249v2 |
2004-06-25 | Strong electron correlation effects in non-volatile electronic memory devices | We investigate hysteresis effects in a model for non-volatile memory devices.
Two mechanisms are found to produce hysteresis effects qualitatively similar to
those often experimentally observed in heterostructures of transition metal
oxides. One of them is a novel switching effect based on a metal-insulator
transition due to strong electron correlations at the dielectric/metal
interface. The observed resistance switching phenomenon could be the
experimental realisation of a novel type of strongly correlated electron
device. | 0406646v1 |
2011-07-20 | Effect of pressure on the electronic structure of hcp Titanium | The effect of pressure on the hexagonal close-packed structure of titanium is
investigated. The lattice parameters of the equilibrium structure were
determined in terms of the Gibbs free energy using the Epitaxial Bain Path
method. When this process was repeated for several pressures, the effect of
pressure on the lattice parameters was revealed. The calculated lattice
parameters were in good agreement with the experimental and theoretical
results. The effects of pressure on parameters depending on the electronic
structure such as conductivity and resistivity in the ground state were also
investigated up to 30 GPa using density functional theory. | 1107.3948v1 |
2014-10-03 | Enhanced spin-orbit coupling and charge carrier density suppression in LaAl1-xCrxO3/SrTiO3 heterointerfaces | We report a gradual suppression of the two-dimensional electron gas (2DEG) at
the LaAlO3/SrTiO3 interface on substitution of chromium at the Al sites. The
sheet carrier density at the interface (ns) drops monotonically from 2.2x10(14)
cm-2 to 2.5x10(13) cm-2 on replacing nearly 60 percent of Al sites by Cr and
the sheet resistance (Rs) exceeds the quantum limit for localization (h/2e2) in
the concentrating range 40 to 60 percent of Cr. | 1410.0876v1 |
2014-10-05 | Planar Hall effect in Y3Fe5O12(YIG)/IrMn films | The planar Hall effect of IrMn on an yttrium iron garnet (YIG = Y3Fe5O12) was
measured in the magnetic field rotating in the film plane. The magnetic field
angle dependence of planar Hall resistance (PHR) has been observed in YIG/IrMn
bilayer at different temperatures, while the GGG/IrMn (GGG= Gd3Ga5O12) shows
constant PHR for different magnetic field angles at both 10 K and 300 K. This
provides evidence that IrMn has interfacial spins which can be led by FM in
YIG/IrMn structure. A hysteresis can be observed in PHR-magnetic field angle
loop of YIG/IrMn films at 10 K, indicating the irreversible switching of IrMn
interfacial spins at low temperature. | 1410.1112v1 |
2014-11-08 | Correlations among magnetic, magnetocaloric and magneto-transport properties in HoNiSi | Magnetic, magnetocaloric and magneto-transport properties of polycrystalline
HoNiSi have been studied. The compound crystallizes in orthorhombic crystal
structure and orders antiferromagnetically at TN=4.6 K. Magnetization isotherms
show curvature at small fields, revealing a field induced metamagnetic
transition. Magnetocalroic effect (MCE) has been estimated using magnetization
data and is found to be 12.8 J/kg K for a field of 50 kOe. Application of field
reduces the resistivity near TN, which results in a large negative MR. The
maximum value of MR has been found to be -24% at 4 K for 50 kOe. Below 4 K, the
compound shows positive MR with shape changing with field. | 1411.2135v1 |
2017-01-29 | Yielding Transitions and Grain-Size Effects in Dislocation Theory | The statistical-thermodynamic dislocation theory developed in previous papers
is used here in an analysis of yielding transitions and grain-size effects in
polycrystalline solids. Calculations are based on the 1995 experimental results
of Meyers et al. for polycrystalline copper under strain-hardening conditions.
The main assertion is that the well known Hall-Petch effects are caused by
enhanced strengths of dislocation sources at the edges of grains instead of the
commonly assumed resistance to dislocation flow across grain boundaries. The
theory describes rapid transitions between elastic and plastic deformation at
yield points; thus it can be used to predict grain-size dependence of both
yield stresses and flow stresses | 1701.08336v1 |
2017-11-08 | Rattler-induced aging dynamics in jammed granular systems | Granular materials jam when developing a network of contact forces able to
resist the applied stresses. Through numerical simulations of the dynamics of
the jamming process, we show that the jamming transition does not occur when
the kinetic energy vanishes. Rather, as the system jams, the kinetic energy
becomes dominated by rattlers particles, that scatter withing their cages. The
relaxation of the kinetic energy in the jammed configuration exhibits a double
power-law decay, which we interpret in terms of the interplay between backbone
and rattlers particles. | 1711.03045v1 |
2017-12-04 | A two-channel model for Spin-relaxation noise | We develop a two-channel resistor model for simulating spin transport with
general applicability. Using this model, for the case of graphene as a
prototypical material, we calculate the spin signal consistent with
experimental values. Using the same model we also simulate the charge and spin-
dependent 1/f noise, both in the local and nonlocal four-probe measurement
schemes, and identify the noise from the spin-relaxation resistances as the
major source of spin-dependent 1/f noise. | 1712.01414v1 |
2018-10-17 | Interface enhanced magnetic anisotropy in Pt/EuO films | We report proximity effects of spin-orbit coupling in EuO$_{1-x}$ films
capped with a Pt overlayer. Transport measurements suggest that current flows
along a conducting channel at the interface between the Pt and EuO. The
temperature dependence of the resistivity picks up the critical behaviors of
EuO, i.e., the metal-to-insulator transition. We also find an unusual
enhancement of the magnetic anisotropy in this structure from its bulk value
which results from strong spin-orbit coupling across the Pt/EuO interface. | 1810.07336v1 |
2018-10-18 | Superconductivity of platinum hydride | We report the ac magnetic susceptibility, electrical resistance, and X-ray
diffraction measurements of platinum hydride (PtHx) in diamond anvil cells,
which reveal its superconducting transition. At 32 GPa, when PtHx is in a
P63/mmc structure, PtHx exhibits superconducting transition at 6.7 K and
superconducting transition temperature (Tc) decreases with pressure to 4.8 K at
36 GPa. The observed T c is higher than that of powdered Pt by more than three
orders of magnitude. It is suggested that hydrides of noble metals have higher
Tc than the elements. | 1810.08191v1 |
2018-10-23 | Perfect absorption of water waves by linear or nonlinear critical coupling | We report on experiments of perfect absorption for surface gravity waves
impinging a wall structured by a subwavelength resonator. By tuning the
geometry of the resonator, a balance is achieved between the radiation damping
and the intrinsic viscous damping, resulting in perfect absorption by critical
coupling. Besides, it is shown that the resistance of the resonator, hence the
intrinsic damping, can be controlled by the wave amplitude, which provides a
way for perfect absorption tuned by nonlinear mechanisms. The perfect absorber
that we propose, without moving parts or added material, is simple, robust and
it presents a deeply subwavelength ratio wavelength/size $\simeq 18$. | 1810.09884v1 |
2018-10-24 | On the effect of Ti on Oxidation Behaviour of a Polycrystalline Nickel-based Superalloy | Titanium is commonly added to nickel superalloys but has a well-documented
detrimental effect on oxidation resistance. The present work constitutes the
first atomistic-scale quantitative measurements of grain boundary and bulk
compositions in the oxide scale of a current generation polycrystalline nickel
superalloy performed through atom probe tomography. Titanium was found to be
particularly detrimental to oxide scale growth through grain boundary
diffusion. | 1810.10444v1 |
2018-10-31 | Domain formation and self-sustained oscillations in quantum cascade lasers | We study oscillations in quantum cascade lasers due to traveling electric
field domains, which are observed both in simulations and experiments. These
oscillations occur in a range of negative differential resistance and we
clarify the condition determining whether the boundary between domains of
different electric field can become stationary. | 1810.13207v2 |
2019-05-01 | Degenerately Doped Transition Metal Dichalcogenides as Ohmic Homojunction Contacts to Transition Metal Dichalcogenide Semiconductors | In search of an improved strategy to form low resistance contacts to MoS2 and
related semiconducting transition metal dichalcogenides, we use ab initio
density functional electronic structure calculations in order to determine the
equilibrium geometry and electronic structure of MoO3/MoS2 and MoO2/MoS2
bilayers. Our results indicate that, besides a rigid band shift associated with
charge transfer, the presence of molybdenum oxide modifies the electronic
structure of MoS2 very little. We find that the charge transfer in the bilayer
provides a sufficient degree of hole doping to MoS2, resulting in a highly
transparent contact region. | 1905.00285v1 |
2019-07-08 | Effect of elasto-plastic compatibility of grains on the void initiation criteria in low carbon steel | The present study evidences the role of ferrite grain size distributions on
the occurrence of void initiation in a low carbon steel. Various
thermomechanical treatments were done to create ultrafine, bimodal and coarse
range of ferrite grain distributions. A two parameter characterization of
probable void initiation sites is proposed; elastic modulus difference and
difference in Schmid factor of the grains surrounding the void. All
microstructures were categorized based on the ability to ease or resist void
nucleation. For coarse grains, elastic modulus difference as well as the Schmid
factor difference is highest, intermediate for ultrafine and lowest for bimodal
microstructure. | 1907.03703v1 |
2020-09-26 | Heat vortexes of ballistic, diffusive and hydrodynamic phonon transport in two-dimensional materials | In this work, the heat vortexes in two-dimensional porous or ribbon
structures are investigated based on the phonon Boltzmann transport equation
(BTE) under the Callaway model. First, the separate thermal effects of normal
(N) scattering and resistive (R) scattering are investigated with
frequency-independent assumptions. And then the heat vortexes in graphene are
studied as a specific example. It is found that the heat vortexes can appear in
both ballistic (rare R/N scattering) and hydrodynamic (N scattering dominates)
regimes but disappear in the diffusive (R scattering dominates) regime. As long
as there is not sufficient R scattering, the heat vortexes can appear in
present simulations. | 2009.12587v1 |
2007-10-17 | Input Impedance, Nanocircuit Loading, and Radiation Tuning of Optical Nanoantennas | Here we explore the radiation features of optical nanoantennas, analyzing the
concepts of input impedance, optical radiation resistance, impedance matching
and loading of plasmonic nanodipoles. We discuss how the concept of antenna
impedance may be applied to optical frequencies, and how its quantity may be
properly defined and evaluated. We exploit these concepts in optimization of
nanoantenna loading by optical nanocircuit elements, extending classic concepts
of radio-frequency antenna theory to the visible regime for the proper design
and matching of plasmonic nanoantennas. | 0710.3411v1 |
2012-01-06 | Bi(111) thin film with insulating interior but metallic surfaces | The electrical conductance of molecular beam epitaxial Bi on BaF2(111) was
measured as a function of both film thickness (4-540 nm) and temperature (5-300
K). Unlike bulk Bi as a prototype semimetal, the Bi thin films up to 90 nm are
found to be insulating in the interiors but metallic on the surfaces. This
result has not only resolved unambiguously the long controversy about the
existence of semimetal-semiconductor transition in Bi thin film but also
provided a straightforward interpretation for the long-puzzled temperature
dependence of the resistivity of Bi thin films, which in turn might suggest
some potential applications in spintronics. | 1201.1480v1 |
2012-01-30 | Thermoelectric Properties of Ho-doped Bi1-xSbx | The Seebeck coefficients, electrical resistivities, total thermal
conductivities, and magnetization are reported for temperatures between 5 and
350 K for n-type Bi0.88Sb0.12 nano-composite alloys made by Ho-doping at the 0,
1 and 3% atomic levels. The alloys were prepared using a dc hot-pressing
method, and are shown to be single phase for both Ho contents with grain sizes
on the average of 900 nm. We find the parent compound has a maximum of ZT =
0.28 at 231 K, while doping 1% Ho increases the maximum ZT to 0.31 at 221 K and
the 3% doped sample suppresses the maximum ZT = 0.24 at a temperature of 260 K. | 1201.6304v1 |
2016-03-21 | Multi-scale modelling of supercapacitors: From molecular simulations to a transmission line model | We perform molecular dynamics simulations of a typical nanoporous-carbon
based supercapacitors. The organic electrolyte consists in
1-ethyl-3-methyl--imidazolium and hexafluorophosphate ions dissolved in
acetonitrile. We simulate systems at equilibrium, for various applied voltages.
This allows us to determine the relevant thermodynamic (capacitance) and
transport (in-pore resistivities) properties. These quantities are then
injected in a transmission line model for testing its ability to predict the
charging properties of the device. The results from this macroscopic model are
in good agreement with non-equilibrium molecular dynamics simulations, which
validates its use for interpreting electrochemical impedance experiments. | 1603.06640v1 |
2017-05-11 | Tunable spin dynamics in chiral soliton lattice | We study dynamics of a chiral soliton lattice (CSL) in a classical
one-dimensional spin chain coupled to the conduction electrons under an
electric field. The CSL has attracted much interest because its period can be
easily controlled by an external magnetic field. We clarify the dependence of
the CSL dynamics on its period. A collective coordinate and an SU(2) gauge
method are used for the analysis. It turns out that the velocity of the CSL
becomes slower as the period becomes longer. We also mention a relation between
the velocity and the magnetic resistance. | 1705.04086v2 |
2017-07-05 | Surfing Liquid Metal Droplet on the Same Metal Bath via Electrolyte Interface | We reported a phenomenon that when exerting an electric field gradient across
a liquid metal/electrolyte interface, a droplet of the same liquid metal can
persistently surf on the interface without coalescence. A thin layer of the
intermediate solution, which separates the droplet from direct metallic
contacting and provides the levitating force, is responsible for such surfing
effect. The electric resistance of this solution film is measured and the film
thickness is further theoretically calculated. The fact that the levitating
state can be switched on and off via a controlled manner paves a way for
reliable manipulation of liquid metal droplet. | 1707.01498v1 |
2018-08-04 | Toward a Spectral Theory of Cellular Sheaves | This paper outlines a program in what one might call spectral sheaf theory
--- an extension of spectral graph theory to cellular sheaves. By lifting the
combinatorial graph Laplacian to the Hodge Laplacian on a cellular sheaf of
vector spaces over a regular cell complex, one can relate spectral data to the
sheaf cohomology and cell structure in a manner reminiscent of spectral graph
theory. This work gives an exploratory introduction, and includes results on
eigenvalue interlacing, sparsification, effective resistance, and sheaf
approximation. These results and subsequent applications are prefaced by an
introduction to cellular sheaves and Laplacians. | 1808.01513v2 |
2018-08-05 | Role of Doping Ratio on The Sensing Properties of ZnO:SnO2 Thin Films | Thin films of ZnO:SnO2 were deposited on different substrates like glass and
c-Si using spray pyrolysis method .The structures and morphology of the
prepared samples films were cheeked using X-ray diffraction and atomic force
microscope. Gas sensing measurements provided from resistance measurement in
the absent and exposure to NO2 gas . The results showed that good enhancement
of sensitivity take place after doping with tin oxide. Maximum sensitivity
obtained at 9% doping ratio and operating temperature 200oC. | 1808.04235v1 |
2018-08-14 | Short commentary on comparing previous claim of RT superconductivity with the data of arXiv:1807.08572, "Evidence for Superconductivity at Ambient Temperature and Pressure in Nanostructures" | I briefly mention a previous claim of room temperature superconductivity (
arXiv:0905.3524) in Ag-based oxide material and compare their results with the
most recent claim of ambient temperature superconductivity in arXiv:1807.08572.
In both cases, an electrical transition to low resistance state and
diamagnetism are observed. Silver is a common ingredient in both claims. Does
it mean that silver holds the key to RT superconductivity or, the missing field
cool data (in both reports) hint of some other physical phenomenon than
superconductivity. | 1808.04912v1 |
2019-03-08 | Ti surface modification for biomedical applications | Micro Arc Oxidation (MAO) is an electrochemical approach for the surface
treatment usually applied on so called valve metals such as Al, Mg and Ti. MAO
is usually carried out an aqueous electrolyte, which involves a bath cooling
and leads to the creation of surface contained components originated in the
electrolyte. In current work, we applied a different approach of ceramic
surface formation on Ti alloy used in biomedical applications. Here, MAO
process conducted in molten nitrate salt at 280 deg C. The developed surface
morphology, chemical and phase composition, and corrosion resistance were
investigated and described in the work. | 1903.03507v1 |
2019-08-22 | Anomalous Hall effect at the spontaneously electron-doped polar surface of PdCoO2 ultrathin films | We revealed the electrical transport through surface ferromagnetic states of
a nonmagnetic metal PdCoO2. Electronic reconstruction at the Pd-terminated
surface of PdCoO2 induces Stoner-like ferromagnetic states, which could lead to
spin-related phenomena among the highly conducting electrons in PdCoO2.
Fabricating a series of nanometer-thick PdCoO2 thin films, we detected a
surface-magnetization-driven anomalous Hall effect via systematic thickness-
and termination-dependent measurements. Besides, we discuss that finite
magnetic moments in electron doped CoO2 triangular lattices may have given rise
to additional unconventional Hall resistance. | 1908.08173v1 |
2011-04-12 | Upper critical fields and superconducting anisotropy of K0.70Fe1.55Se1.01S0.99 and K0.76Fe1.61Se0.96S1.04 single crystals | We have investigated temperature and angular dependence of resistivity of
K0.70(7)Fe1.55(7)Se1.01(2)S0.99(2) and K0.76(5)Fe1.61(5)Se0.96(4)S1.04(5)
single crystals. The upper critical fields Hc2(T) for both field directions
decrease with the increase in S content. On the other hand, the angle-dependent
magnetoresistivity for both compounds can be scaled onto one curve using the
anisotropic Ginzburg-Landau theory. The obtained anisotropy of Hc2(T) increases
with S content, implying that S doping might decrease the dimensionality of
certain Fermi surface parts, leading to stronger two dimensional character. | 1104.2318v2 |
2012-03-10 | Large thermal Hall coefficient in bismuth | We present a systematical study of thermal Hall effect on a bismuth single
crystal by measuring resistivity, Hall coefficient, and thermal conductivity
under magnetic field, which shows a large thermal Hall coefficient comparable
to the largest one in a semiconductor HgSe. We discuss that this is mainly due
to a large mobility and a low thermal conductivity comparing theoretical
calculations, which will give a route for controlling heat current in
electronic devices. | 1203.2237v1 |
2012-06-12 | Evidence of Josephson-coupled superconducting regions at the interfaces of Highly Oriented Pyrolytic Graphite | Transport properties of a few hundreds of nanometers thick (in the graphene
plane direction) lamellae of highly oriented pyrolytic graphite (HOPG) have
been investigated. Current-Voltage characteristics as well as the temperature
dependence of the voltage at different fixed input currents provide evidence
for Josephson-coupled superconducting regions embedded in the internal
two-dimensional interfaces, reaching zero resistance at low enough
temperatures. The overall behavior indicates the existence of superconducting
regions with critical temperatures above 100 K at the internal interfaces of
oriented pyrolytic graphite. | 1206.2463v2 |
2012-06-20 | Enhanced thermoelectric properties by Ir doping of PtSb2 with pyrite structure | The effects of Ir doping on the thermoelectric properties of Pt1-xIrxSb2 (x =
0, 0.01, 0.03, and 0.1) with pyrite structure were studied. Measurements of
electrical resistivity rho, Seebeck coefficient S, and thermal conductivity
kappa were conducted. The results showed an abrupt change from semiconducting
behavior without Ir (x = 0) to metallic behavior at x = 0.01. The sample with x
= 0.01 exhibited large S and low rho, resulting in a maximum power factor
(S^2/rho) of 43 muW/cmK^2 at 400 K. The peculiar "pudding mold"-type electronic
band dispersion could explain the enhanced thermoelectric properties in the
metallic state. | 1206.4482v1 |
2012-06-28 | Electron backscattering from stacking faults in SiC by means of \textit{ab initio} quantum transport calculations | We study coherent backscattering phenomena from single and multiple stacking
faults (SFs) in 3C- and 4H-SiC within density functional theory quantum
transport calculations. We show that SFs give rise to highly dispersive bands
within both the valance and conduction bands that can be distinguished for
their enhanced density of states at particular wave number subspaces. The
consequent localized perturbation potential significantly scatters the
propagating electron waves and strongly increases the resistance for $n$-doped
systems. We argue that resonant scattering from SFs should be one of the
principal degrading mechanisms for device operation in silicon carbide. | 1206.6600v1 |
2015-04-28 | Optical loss by surface transfer doping in silicon waveguides | We show that undoped silicon waveguides may suffer of up to 1.8 dB/cm
free-carrier absorption caused by improper surface passivation. To verify the
effects of free-carriers we apply a gate field to the waveguides. Smallest
losses correspond to higher electrical sheet resistances and are generally
obtained with non-zero gate fields. The presence of free carriers for zero gate
field is attributed to surface transfer doping. These results open new
perspectives for minimizing propagation losses in silicon waveguides and for
obtaining low-loss and highly conductive silicon films without applying a gate
voltage. | 1504.07613v1 |
2015-07-04 | Evidence for defect-mediated tunneling in hexagonal boron nitride-based junctions | We investigate tunneling in metal-insulator-metal junctions employing few
atomic layers of hexagonal boron nitride (hBN) as the insulating barrier. While
the low-bias tunnel resistance increases nearly exponentially with barrier
thickness, subtle features are seen in the current-voltage curves, indicating
marked influence of the intrinsic defects present in the hBN insulator on the
tunneling transport. In particular, single electron charging events are
observed, which are more evident in thicker-barrier devices where direct
tunneling is substantially low. Furthermore, we find that annealing the devices
modifies the defect states and hence the tunneling signatures. | 1507.01058v1 |
2015-07-13 | Defect induced structural and thermoelectric properties of Sb2Te3 alloy | Structural and thermoelectric properties of metallic and semiconducting
Sb2Te3 are reported. X-Ray diffraction and Raman spectroscopy studies reveal
that semiconducting sample have higher defect density. Nature and origin of
possible defects are highlighted. Semiconducting Sb2Te3 hosts larger numbers of
defects, which act as scattering center and give rise to the increased value of
resistivity, thermopower and power factor. Thermopower data indicates p-type
nature of the synthesized samples. It is evidenced that the surface states are
often mixed with the bulk state, giving rise to metallicity in Sb2Te3. Role of
different scattering mechanism on the thermoelectric property of Sb2Te3 is
discussed. | 1507.03337v1 |
2015-07-22 | Theoretical Study of Coulomb Correlations and Spin-Orbit Coupling in SrIrO3 | Given that energy scales associated with crystal field splitting, spin orbit
coupling and coulomb correlations in iridates are comparable, hence leading to
exotic properties, we investigate the physical properties of orthorhombic
SrIrO3 using density functional theory. Our calculations, however, show that
SrIrO 3 is a bad metal with no long range magnetic ordering, unlike its sister
compounds Sr2IrO4 and Sr3Ir2O7. Moreover, despite having large band width, it
appears conclusive that the larger resistivity in SrIrO 3 is due to spin orbit
interactions. Besides, the effects of electron-electron correlations on its
electronic structure and magnetic properties are also discussed. | 1507.06058v1 |
2016-09-21 | Spin Hall magnetoresistance in antiferromagnet/normal metal bilayers | We predict the emergence of spin Hall magnetoresistance in a magnetic bilayer
composed of a normal metal adjacent to an antiferromagnet. Based on a recently
derived drift-diffusion equation, we show that the resistance of the bilayer
depends on the relative angle between the direction transverse to the current
flow and the N\'eel order parameter. Although this effect presents striking
similarities with the spin Hall magnetoresistance recently reported in
ferromagnetic bilayers, in the present case its physical origin is attributed
to the anisotropic spin relaxation of itinerant spins in the antiferromagnet. | 1609.06521v1 |
2018-12-26 | Probing the Relationship between Anisotropic Magnetoresistance and Magnetization of ferromagnetic films | The anisotropic magnetoresistance (AMR) in thin permalloy strips was
calculated at each steps during magnetization by the finite element method. The
magnetization at equilibrium under different external fields was obtained by
micromagnetic simulations, while the resistance with different magnetization
was obtained by solving the Poisson equations iteratively until
self-consistence. We find that the relation between magnetization and AMR
deviates from the Stoner-Wohlfarth prediction when the magnetization is reduced
from saturation. The reason is that the demagnetization is not necessarily from
coherent rotation of the magnetic moment. We conclude that it is necessary to
use numeric simulations to optimize the responses of AMR sensors. | 1812.10294v1 |
2019-03-02 | Reconfigurable Electromagnetic Structures: X-Band and Beyond | Developing reconfigurable millimeter-wave (mmWave) antennas and devices is an
outstanding challenge, with switch technologies being a primary impediment.
Recently, it has been shown that vanadium dioxide (VO2), a thermochromic
material whose resistance changes with temperature, could provide a path
forward in developing reconfigurable mmWave devices. As an initial step towards
this vision, we investigate the integration of VO2 switches in reconfigurable
components at 15 GHz. In particular, a frequency reconfigurable antenna and a
reconfigurable phase shifter are shown. The low loss and minimal parasitics of
VO2 technology have the potential to enable devices at 15 GHz and beyond. | 1906.03034v1 |
2019-06-18 | The Poole-Frenkel laws and a pathway to multi-valued memory | We revisit the mechanism of Poole-Frenkel non-ohmic conduction in materials
of non-volatile memory. Percolation theory is shown to explain both the Poole
and Frenkel dependencies corresponding to the cases of respectively small and
large samples compared to the correlation radii of their percolation clusters.
The applied bias modifies a limited number of microscopic resistances forming
the percolation pathways. That understanding opens a pathway to multi-valued
non-volatile memory and related neural network applications. | 1906.07677v2 |
2019-11-06 | Disclosing antiferromagnetism in tetragonal Cr2O3 by electrical measurements | The tetragonal phase of chromium (III) oxide, although unstable in the bulk,
can be synthesized in epitaxial heterostructures. The theoretical investigation
by density functional theory predicts an antiferromagnetic ground state for
this compound. We demonstrate experimentally antiferromagnetism up to 40 K in
ultrathin films of t-Cr2O3 by electrical measurements exploiting interface
effect within a neighboring ultrathin Pt layer. We show that magnetotransport
in Pt is affected by both spin-Hall magnetoresistance and magnetic proximity
effect while we exclude any role of magnetism for the low-temperature
resistance anomaly observed in Pt. | 1911.02596v1 |
2020-06-14 | Ideal memristor based on viscous magnetization dynamics driven by spin torque | We show that ideal memristors - devices whose resistance is proportional to
the charge that flows through them - can be realized using spin torque-driven
viscous magnetization dynamics. The latter can be accomplished in the spin
liquid state of thin-film heterostructures with frustrated exchange, where
memristive response is tunable by proximity to the glass transition, while
current-induced Joule heating facilitates nonvolatile operation and
second-order memristive functionality beneficial for neuromorphic applications.
Ideal memristive behaviors can be achieved in other systems characterized by
viscous dynamics of physical, electronic, or magnetic degrees of freedom. | 2006.07996v1 |
2020-08-17 | Surface Conductivity in Antiferromagnetic Semiconductor CrSb$_2$ | The contribution of bulk and surface to the electrical resistance along
crystallographic \textit{b}- and \textit{c}-axes as a function of crystal
thickness gives evidence for a temperature independent surface states in an
antiferromagnetic narrow-gap semiconductor CrSb$_{2}$. ARPES shows a clear
electron-like pocket at $\Gamma$-$Z$ direction which is absent in the bulk band
structure. First-principles calculations also confirm the existence of metallic
surface states inside the bulk gap. Whereas combined experimental probes point
to enhanced surface conduction similar to topological insulators, surface
states are trivial since CrSb$_2$ exhibits no band inversion. | 2008.07521v1 |
2020-08-23 | Rigidity and fracture of fibrous double networks | Tunable mechanics and fracture resistance are hallmarks of biological tissues
and highly desired in engineered materials. To elucidate the underlying
mechanisms, we study a rigidly percolating double network (DN) made of a stiff
and a flexible network. The DN shows remarkable tunability in mechanical
response when the stiff network is just above its rigidity percolation
threshold and minimal changes far from this threshold. Further, the DN can be
modulated to either be extensible, breaking gradually, or stronger, breaking in
a more brittle fashion by varying the flexible network's concentration. | 2008.09934v1 |
2020-12-23 | Superconducting properties of the non-centrosymmetric Superconductors TaXSi (X= Re, Ru) | We have investigated the ternary noncentrosymmetric superconductors TaXSi
(X=Re, Ru) by magnetization, resistivity, and specific heat measurements. The
samples crystallize in orthorhombic TiFeSi structure having superconducting
transition Tc = 5.32 K and 3.91 K, for TaReSi and TaRuSi respectively. Specific
heat measurements indicated an s-wave nature of both materials with a
moderately coupled nature. However, a low value of specific heat jump and the
concave nature of the upper critical field suggests a nontrivial
superconducting gap. | 2012.12596v1 |
2021-01-30 | Nearly ideal memristive functionality based on viscous magnetization dynamics | We experimentally demonstrate a proof-of-principle implementation of an
almost ideal memristor - a two-terminal circuit element whose resistance is
approximately proportional to the integral of the input signal over time. The
demonstrated device is based on a thin-film ferromagnet/antiferromagnet
bilayer, where magnetic frustration results in viscous magnetization dynamics
enabling memristive functionality, while the external magnetic field plays the
role of the driving input. The demonstrated memristor concept is amenable to
downscaling and can be adapted for electronic driving, making it attractive for
applications in neuromorphic circuits. | 2102.00123v1 |
2021-09-18 | Berry curvature induced nonlinear magnetoresistivity in two dimensional systems | The band geometric properties of quantum materials play an elemental role in
the linear and nonlinear transport of electrons. In this paper, we propose that
the interplay of the Berry curvature, the orbital magnetic moment and the
Lorentz force can induce a finite nonlinear resistivity in two dimensional
systems in presence of a perpendicular magnetic field. The induced nonlinear
magnetoresistivity scales linearly with the magnetic field and is purely
quantum mechanical in origin. This novel transport signature can be used as an
additional experimental probe for the geometric quantities in intrinsically
time reversal symmetric systems. | 2109.08979v2 |
2021-10-28 | Prandtl-Tietjens intermittency in transitional pipe flows | Pipe flow often traverses a regime where laminar and turbulent flow co-exist.
Prandtl and Tietjens explained this intermittency as a feedback between the
fluctuations of the internal flow resistance and the constant pressure drop
driving the flow. However, because the focus has moved towards studying
intermittency without flow fluctuations near the universal critical Reynolds
number, their explanation has largely disappeared. Here we refine the
mechanism, which has never been put to a quantitative test, to develop a model
that agrees with experiments at higher Reynolds numbers, enabling us to
demonstrate that Prandtl and Tietjens' mechanism is, in fact, intrinsic to
flows where both the pressure gradient and perturbation are constant. | 2110.14983v2 |
2021-11-09 | Lattice structure design optimization under localized linear buckling constraints | An optimization method for the design of multi-lattice structures satisfying
local buckling constraints is proposed in this paper. First, the concept of
free material optimization is introduced to find an optimal elastic tensor
distribution among all feasible elastic continua. By approximating the elastic
tensor under the buckling-containing constraint, a matching lattice structure
is embedded in each macro element. The stresses in local cells are especially
introduced to obtain a better structure. Finally, the present method obtains a
lattice structure with excellent overall stiffness and local buckling
resistance, which enhances the structural mechanical properties. | 2111.05294v1 |
2021-11-16 | Have Mysterious Topological Valley Currents Been Observed in Graphene Superlattices? | We provide a critical discussion concerning the claim of topological valley
currents, driven by a global Berry curvature and valley Hall effect proposed in
recent literature. After pointing out a major inconsistency of the theoretical
scenario proposed to interpret giant nonlocal resistance, we discuss various
possible alternative explanations and open directions of research to solve the
mystery of nonlocal transport in graphene superlattices. | 2111.08506v1 |
2021-12-23 | Metal Oxide Nanoparticles and Their Applications: A Report | Herein, we report a brief introduction of metal oxide nanoparticles and their
diverse applications in different scientific and medical fields. This report
will be updated frequently to give a complete review in similar fields of
nanotechnology. In the present version of the report, an introduction to
nanotechnology and nanomaterials with some synthesis routes (such as
Hydrothermal synthesis and Sol-Gel synthesis etc.) to prepare the metal oxide
nanoparticles is given. In this version we have primarily included the basic
introduction of application of metal oxide nanoparticles in the fields of
biomedical, resistive switching and photovoltaic etc. | 2201.04938v1 |
2022-04-14 | Cohesive zone modelling of hydrogen assisted fatigue crack growth: the role of trapping | We investigate the influence of microstructural traps in hydrogen-assisted
fatigue crack growth. To this end, a new formulation combining multi-trap
stress-assisted diffusion, mechanism-based strain gradient plasticity and a
hydrogen- and fatigue-dependent cohesive zone model is presented and
numerically implemented. The results show that the ratio of loading frequency
to effective diffusivity governs fatigue crack growth behaviour. Increasing the
density of \emph{beneficial} traps, not involved in the fracture process,
results in lower fatigue crack growth rates. The combinations of loading
frequency and carbide trap densities that minimise embrittlement susceptibility
are identified, providing the foundation for a rational design of
hydrogen-resistant alloys. | 2204.07079v1 |
2022-06-10 | Magneto-Seebeck coefficient of Fermi-liquid in three-dimensional Dirac/Weyl semimetal | We investigate dissipationless magneto-Seebeck effect in three-dimensional
Dirac/Weyl semimetal. The Hall resistivity $\rho_{yx}$ and thermoelectric Hall
coefficient $\alpha_{xy}$ exhibit plateaus at the quantum limit, where
electrons occupy only the zeroth Landau level. In this condition, quantum
oscillation in the Seebeck coefficient $S_{xx}\approx \rho_{yx}\alpha_{xy} $ is
suppressed, and the massless fermions are transformed into a Fermi liquid
system. We show that the Seebeck coefficient at the quantum limit is expressed
by the harmonic sum of Fermi wavelength and thermal de Broglie wavelength
scaled by magnetic length. | 2206.04957v1 |
2022-06-13 | LinReTraCe: The Linear Response Transport Centre | We describe the "Linear Response Transport Centre" (LinReTraCe), a package
for the simulation of transport properties of solids. LinReTraCe captures
quantum (in)coherence effects beyond semi-classical Boltzmann techniques, while
incurring similar numerical costs. The enabling algorithmic innovation is a
semi-analytical evaluation of Kubo formulae for resistivities and the
coefficients of Hall, Seebeck and Nernst. We detail the program's architecture,
its interface and usage with electronic-structure packages such as WIEN2k,
VASP, and Wannier90, as well as versatile tight-binding settings. | 2206.06097v2 |
2022-08-03 | Electrical transport and magnetic properties of the triangular-lattice compound Zr$_2$NiP$_2$ | We report the first investigation of the electrical and magnetic properties
of the triangular-lattice compound Zr$_2$NiP$_2$ (space group $P$6$_3$/$mmc$).
The temperature evolution of electrical resistivity follows the
Bloch-Gr\"uneisen-Mott law, and exhibits a typically metallic behavior. No
transition is visible by both electrical and magnetic property measurements,
and nearly no magnetization is detected ($M_0$ $<$ 0.002$\mu_\mathrm{B}$/Ni)
down to 1.8 K up to 7 T. The metallic and nonmagnetic characters are well
understood by the first-principles calculations for Zr$_2$NiP$_2$. | 2208.01799v1 |
2022-08-09 | Rapid suppression of charge density wave transition in LaSb2 under pressure | LaSb2 is found to be an example of an exceptionally pressure sensitive and
tunable, two dimensional compound. In-plane electrical resistivity of LaSb2
under pressure up to 12.9 kbar was measured in zero and applied magnetic field.
The charge density wave transition (observed at ~ 350 K at ambient pressure) is
completely suppressed by 6-7 kbar with significant (in comparison with the
ambient pressure) increase in Fermi surface gapping and transition hysteresis
just above ambient pressure. | 2208.04997v1 |
2023-03-12 | Pressure-induced color change in the lutetium dihydride LuH2 | The lutetium dihydride LuH2 is stable at ambient conditions. Here we show
that its color undergoes sequential changes from dark blue at ambient pressure
to pink at ~2.2 GPa and then to bright red at ~4 GPa upon compression in a
diamond anvil cell. Such a pressure-induced color change in LuH2 is reversible
and it is very similar to that recently reported in the N-doped lutetium
hydride. However, our preliminary resistance measurements on LuH2 under
pressures up to 7.7 GPa evidenced no superconductivity down to 1.5 K. | 2303.06718v1 |
2023-06-27 | Enhancing interfacial thermal conductance of amorphous interface by optimized interfacial mass distribution | Interfacial thermal resistance arises challenges for the thermal management
as the modern semiconductors are miniatured to nanoscale. Previous studies
found that graded mass distribution in interface can maximumly enhance the
interfacial thermal conductance of crystalline interface, however, whether this
strategy is effective for amorphous interface is less explored. In this work,
graded mass distribution in the amorphous interface between crystalline Si and
crystalline Ge is optimized to increase the interfacial thermal conductance by
the extended atomistic Greens function method. | 2306.15254v1 |
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