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2012-05-15
Field-induced high coercive ferromagnetic state and magnetoresistance in the antiferromagnetically ordered compound Fe0.5TiS2
The measurements of the magnetic susceptibility, magnetization, electrical resistivity and magnetoresistance have been performed for the Fe intercalated compound Fe0.5TiS2. According to X-ray diffraction measurements the Fe0.5TiS2 compound synthesized in the present work has a monoclinic crystal structure (space group ...
1205.3242v1
2012-05-16
A new approach for improving global critical current density in Fe(Se0.5Te0.5) polycrystalline materials
A novel method to prepare bulk Fe(Se0.5Te0.5) samples is presented, based on a melting process and a subsequent annealing treatment. With respect to the standard sintering technique, it produces much more homogeneous and denser samples, characterized by large and well interconnected grains. The resulting samples exhibi...
1205.3618v2
2012-05-29
Transformation Electronics: Tailoring Electron's Effective Mass
The speed of integrated circuits is ultimately limited by the mobility of electrons or holes, which depend on the effective mass in a semiconductor. Here, building on an analogy with electromagnetic metamaterials and transformation optics, we describe a new transport regime in a semiconductor superlattice characterized...
1205.6325v2
2012-07-13
Association of indigo with zeolites for improved colour stabilization
The durability of an organic colour and its resistance against external chemical agents and exposure to light can be significantly enhanced by hybridizing the natural dye with a mineral. In search for stable natural pigments, the present work focuses on the association of indigo blue with several zeolitic matrices (LTA...
1207.3236v1
2012-08-09
The role of charge traps in inducing hysteresis: capacitance - voltage measurements on top gated bilayer graphene
Understanding the origin of hysteresis in the channel resistance from top gated graphene transistors is important for transistor applications. Capacitance - voltage measurements across the gate oxide on top gated bilayer graphene show hysteresis with a charging and discharging time constant of ~100 {\mu}s. However, the...
1208.1831v1
2012-08-15
A GEANT4 Simulation Studyof BESIII endcap TOF Upgrade
A GEANT4-based Monte-Carlo model is developed to study the performance of Endcap Time-Of-Flight (ETOF) at BESIII. It's found that the multiple scattering effects, mainly from the materials at the MDC endcap, can cause multi-hit on the ETOF's readout cell and significantly influence the timing property of ETOF. Multi-ga...
1208.3049v1
2012-09-03
High Efficiency Graphene Solar Cells by Chemical Doping
We demonstrate single layer graphene/n-Si Schottky junction solar cells that under AM1.5 illumination exhibit a power conversion efficiency (PCE) of 8.6%. This performance, achieved by doping the graphene with bis(trifluoromethanesulfonyl)amide, exceeds the native(undoped) device performance by a factor of 4.5 and the ...
1209.0432v1
2012-09-12
Channel Length Scaling of MoS2 MOSFETs
In this article, we investigate electrical transport properties in ultrathin body (UTB) MoS2 two-dimensional (2D) crystals with channel lengths ranging from 2 {\mu}m down to 50 nm. We compare the short channel behavior of sets of MOSFETs with various channel thickness, and reveal the superior immunity to short channel ...
1209.2525v1
2012-09-24
Ba1-xNaxTi2Sb2O (0.0 <= x <= 0.33): A Layered Titanium-based Pnictide Oxide Superconductor
A new layered Ti-based pnictide oxide superconductor, Ba1-xNaxTi2Sb2O (0.0 <= x <= 0.33), is reported. X-ray studies reveal it crystallizes in the tetragonal CeCr2Si2C structure. The undoped parent compound, BaTi2Sb2O (P4/mmm; a=4.1196(1){\AA}; c=8.0951(2){\AA}), exhibits a CDW/SDW transition at 54K. Upon chemical dopi...
1209.5447v2
2012-09-27
Fabrication and characterization of semiconducting half Heusler YPtSb thin films
The semiconducting half Heusler compound YPtSb was predicted theoretically to be capable of changing into topological insulator under proper strain. In this work, p type semiconducting half-Heusler YPtSb thin films were prepared by magnetron co-sputtering method from a specially designed target for the first time. Text...
1209.6288v2
2012-10-08
Phonon thermal transport outside of local equilibrium in nanowires via molecular dynamics
We study thermal transport through Pt nanowires that bridge planar contacts as a function of wire length and vibrational frequency of the contacts. When phonons in the contacts have lower average frequencies than those in the wires thermal transport occurs under conditions away from local equilibrium with low-frequency...
1210.2321v1
2012-10-19
Self-aligned graphene field-effect transistors with polyethyleneimine doped source/drain access regions
We report a method of fabricating self-aligned, top-gated graphene field-effect transistors (GFETs) employing polyethyleneimine spin-on-doped source/drain access regions, resulting in a 2X reduction of access resistance and a 2.5X improvement in device electrical characteristics, over undoped devices. The GFETs on Si/S...
1210.5535v2
2012-10-22
Fabrication and characterization of the gapless half-Heusler YPtSb thin films
Half-Heusler YPtSb thin films were fabricated by magnetron co-sputtering method on MgO-buffered SiO2/Si(001) substrates. X-ray diffraction pattern and Energy dispersive X-ray spectroscopy confirmed the high-quality growth and stoichiometry. The temperature dependence of the resistivity shows a semiconducting-type behav...
1210.5808v1
2012-10-29
Impact of graphene quantum capacitance on transport spectroscopy
We demonstrate experimentally that graphene quantum capacitance $C_{\mathrm{q}}$ can have a strong impact on transport spectroscopy through the interplay with nearby charge reservoirs. The effect is elucidated in a field-effect-gated epitaxial graphene device, in which interface states serve as charge reservoirs. The F...
1210.7601v1
2012-11-02
Interface characterization of Co2MnGe/Rh2CuSn Heusler multilayers
All-Heusler multilayer structures have been investigated by means of high kinetic x-ray photoelectron spectroscopy and x-ray magnetic circular dichroism, aiming to address the amount of disorder and interface diffusion induced by annealing of the multilayer structure. The studied multilayers consist of ferromagnetic Co...
1211.0489v2
2012-11-13
The giant plasticity of a quantum crystal
When submitted to large stresses at high temperature, usual crystals may irreversibly deform. This phenomenon is known as plasticity and it is due to the motion of crystal defects such as dislocations. We have discovered that, in the absence of impurities and in the zero temperature limit, helium 4 crystals present a g...
1211.2976v2
2012-11-14
High-temperature structural phase transition in multiferroic LiCu_2O_2
LiCu_2O_2 single crystals were studied in the temperature range 300-1100 K by means of heating-cooling curves of differential thermal analysis (DTA), thermogravimetry (TG), X-ray powder diffraction and electrical measurements. A reversible first-order phase transition between orthorhombic and tetragonal phases was foun...
1211.3275v1
2012-11-14
Anisotropy and directional pinning in YBaCuO with BaZrO3 nanorods
Measurements of anisotropic transport properties (dc and high-frequency regime) of driven vortex matter in YBa$_2$Cu$_3$O$_{7-x}$ with elongated strong-pinning sites (c-axis aligned, self-assembled BaZrO$_3$ nanorods) are used to demonstrate that the effective-mass angular scaling takes place only in intrinsic physical...
1211.3311v2
2012-11-23
1D to 3D Dimensional Crossover in the Superconducting Transition of the Quasi-One-Dimensional Carbide Superconductor Sc3CoC4
The transition metal carbide superconductor Sc3CoC4 may represent a new benchmark system of quasi-1D superconducting behavior. We investigate the superconducting transition of a high-quality single crystalline sample by electrical transport experiments. Our data show that the superconductor goes through a complex dimen...
1211.5430v4
2012-11-26
Local transport measurements at mesoscopic length scales using scanning tunneling potentiometry
Under mesoscopic conditions, the transport potential on a thin film with current is theoretically expected to bear spatial variation due to quantum interference. Scanning tunneling potentiometry is the ideal tool to investigate such variation, by virtue of its high spatial resolution. We report in this {\it Letter} the...
1211.6088v2
2012-12-06
Effects of spin density wave quantization on the electrical transport in epitaxial Cr thin films
We present measurements of the electrical resistivity, $\rho$, in epitaxial Cr films of different thicknesses grown on MgO (100) substrates, as a function of temperature, $T$. The $\rho(T)$ curves display hysteretic behavior in certain temperature range, which is film thickness dependent. The hysteresis are related to ...
1212.1408v1
2013-01-09
Hall effect measurements on epitaxial SmNiO3 thin films and implications for antiferromagnetism
The rare-earth nickelates (RNiO3) exhibit interesting phenomena such as unusual antiferromagnetic order at wavevector q = (1/2, 0, 1/2) and a tunable insulator-metal transition that are subjects of active research. Here we present temperature-dependent transport measurements of the resistivity, magnetoresistance, Seebe...
1301.1968v3
2013-01-11
Batch-fabricated cantilever probes with electrical shielding for nanoscale dielectric and conductivity imaging
This paper presents the design and fabrication of batch-processed cantilever probes with electrical shielding for scanning microwave impedance microscopy. The diameter of the tip apex, which defines the electrical resolution, is less than 50 nm. The width of the stripline and the thicknesses of the insulation dielectri...
1301.2402v1
2013-01-14
Pressure-Induced Superconductivity and Its Scaling with Doping-Induced Superconductivity in the Iron Pnictide with Skutterudite Intermediary Layers
The Ca10(PtnAs8)(Fe2As2)5 (n=3,4) compounds are a new type of iron pnictide superconductors whose structures consist of stacking Ca-PtnAs8-Ca-Fe2As2 layers in a unit cell. When n=3 (the 10-3-8 phase), the undoped compound is an antiferromagnetic (AFM) semiconductor, while, when n=4 (the 10-4-8 phase), the undoped compo...
1301.2863v2
2013-02-08
Electrical transport across Au/Nb:SrTiO3 Schottky interface with different Nb doping
We have investigated electron transport in Nb doped SrTiO$_3$ single crystals for two doping densities. We find that the resistivity and mobility are temperature dependent in both whereas the carrier concentration is almost temperature invariant. We rationalize this using the hydrogenic theory for shallow donors. Furth...
1302.2096v1
2013-02-14
Transport studies of dual-gated ABC and ABA trilayer graphene: band gap opening and band structure tuning in very large perpendicular electric field
We report on the transport properties of ABC and ABA stacked trilayer graphene using dual, locally gated field effect devices. The high efficiency and large breakdown voltage of the HfO2 top and bottom gates enables independent tuning of the perpendicular electric field and the Fermi level over an unprecedentedly large...
1302.3432v1
2013-02-21
Superconductivity induced by U-doping in the SmFeAsO system
Through partial substitution of Sm by U in SmFeAsO, a different member of the family of iron-based superconductors was successfully synthesized. X-ray diffraction measurements show that the lattice constants along the a and c axes are both squeezed through U doping, indicating a successful substitution of U at the Sm s...
1302.5155v1
2013-04-10
Pinning in a Porous Bi2223
The current-voltage characteristics of a porous superconductor Bi2Sr2Ca2Cu3Ox (Bi2223) have been measured at temperature range from 10 to 90 K. The experimental dependences have been analyzed within the model allowing for pinning by clusters of a normal phase with fractal boundaries, as well as the model taking into ac...
1304.2844v1
2013-04-10
Multi-band superconductivity and nanoscale inhomogeneity at oxide interfaces
The two-dimensional electron gas at the LaTiO3/SrTiO3 or LaAlO3/SrTiO3 oxide interfaces becomes superconducting when the carrier density is tuned by gating. The measured resistance and superfluid density reveal an inhomogeneous superconductivity resulting from percolation of filamentary structures of superconducting "p...
1304.2970v1
2013-04-22
Electrical transport in C-doped GaAs nanowires: surface effects
The resistivity and the mobility of Carbon doped GaAs nanowires have been studied for different doping concentrations. Surface effects have been evaluated by comparing upassivated with passivated nanowires. We directly see the influence of the surface: the pinning of the Fermi level and the consequent existence of a de...
1304.5891v1
2013-05-23
Electronic origin of the orthorhombic Cmca structure in compressed elements and binary alloys
Formation of the complex structure with 16 atoms in the orthorhombic cell, space group Cmca (Pearson symbol oC16) was experimentally found under high pressure in the alkali elements (K, Rb, Cs) and polyvalent elements of groups IV (Si, Ge) and V (Bi). Intermetallic phases with this structure form under pressure in bina...
1305.5341v1
2013-05-29
Intrinsic and extrinsic origins of low-frequency noise in GaAs/AlGaAs Schottky-gated nanostructures
We study low-frequency noise in current passing through quantum point contacts fabricated from several GaAs/AlGaAs heterostructures with different layer structures and fabrication processes. In contrast to previous reports, there is no gate-dependent random telegraph noise (RTN) originating from tunneling through a Sch...
1305.6701v1
2013-06-29
Coexistence of Half-Metallic Itinerant Ferromagnetism with Local-Moment Antiferromagnetism in Ba{0.60}K{0.40}Mn2As2
Magnetization, nuclear magnetic resonance, high-resolution x-ray diffraction and magnetic field-dependent neutron diffraction measurements reveal a novel magnetic ground state of Ba{0.60}K{0.40}Mn2As2 in which itinerant ferromagnetism (FM) below a Curie temperature TC = 100 K arising from the doped conduction holes coe...
1307.0091v2
2013-07-22
Dimensional-Crossover-Driven Mott Insulators in SrVO3 Ultrathin Films
High-quality epitaxial SrVO3 (SVO) thin films of various thicknesses were grown on (001)-oriented LSAT substrates by pulsed electron-beam deposition technique. Thick SVO films (~25 nm) exhibited metallic behavior with the electrical resistivity following the T2 law corresponding to a Fermi liquid system. We observed a ...
1307.5819v2
2013-07-26
Electron-phonon coupling in cuprate and iron-based superconductors revealed by Raman scattering
Electron-phonon coupling (EPC) is one of the most common and fundamental interactions in solids. It not only dominates many basic dynamic processes like resistivity, thermal conductivity etc, but also provides the pairing glue in conventional superconductors. But in high-temperature superconductors (HTSC), it is still ...
1307.6972v1
2014-02-10
Evolution and defect analysis of vertical graphene nanosheets
We report catalyst-free direct synthesis of vertical graphene nanosheets (VGNs) on SiO2/Si and quartz substrates using microwave electron cyclotron resonance - plasma enhanced chemical vapor deposition. The evolution of VGNs is studied systematically at different growth stages. Raman analysis as a function of growth ti...
1402.2074v3
2014-02-19
Phase Diagram of Micron-Size Bridges of SrTiO$_3/$LaAlO$_3$ Interface: Link Between Multiple Band Structure and Superconductivity
The rich phase diagram of the two dimensional electron gas (2DEG) at the \STO/\LAO interface is probed using Hall and longitudinal resistivity. Thanks to a special bridge design we are able to tune through the superconducting transition temperature T$_c$ and to mute superconductivity by either adding or removing carrie...
1402.4646v1
2014-03-04
Effect of modulations of doping and strain on the electron transport in monolayer MoS_2
The doping and strain effects on the electron transport of monolayer MoS_2 are systematically investigated using the first-principles calculations with Boltzmann transport theory. We estimate the mobility has a maximum 275 cm^2/(Vs) in the low doping level under the strain-free condition. The applying a small strain (3...
1403.0695v2
2014-03-29
Two components for one resistivity in LaVO3/SrTiO3 heterostructures
A series of 100 nm LaVO3 thin films have been synthesized on (001)-oriented SrTiO3 substrates using the pulsed laser deposition technique, and the effects of growth temperature are analyzed. Transport properties reveal a large electronic mobility and a non-linear Hall effect at low temperature. In addition, a cross-ove...
1403.7648v2
2014-04-07
Directional pinning and anisotropy in YBa2Cu3O7-x with BaZrO3 nanorods: intrinsic and nanorods-induced anisotropy
We present a study of the anisotropic vortex parameters as obtained from measurements of the microwave complex resistivity in the vortex state with a tilted applied magnetic field in YBa2Cu3O7-x thin films with BaZrO3 nanorods. We present the angular dependence of the vortex viscosity $\eta$, the pinning constant k_p a...
1404.1670v1
2014-05-07
Anisotropic giant magnetoresistance in NbSb2
The extremely large transverse magnetoreistance (the magnetoresistant ratio $\sim 1.3\times10^5\%$ in 2 K and 9 T field, and $4.3\times 10^6\%$ in 0.4 K and 32 T field, without saturation), and the metal-semiconductor crossover induced by magnetic field, are reported in NbSb$_2$ single crystal with electric current par...
1405.1719v2
2014-06-05
Current transport and thermoelectric properties of very high power factor Fe3O4 / SiO2 / p-type Si (001) devices
The current transport and thermoelectric properties of Fe3O4 / SiO2 / p-type Si(001) heterostructures with Fe3O4 thicknesses of 150, 200, and 350 nm have been investigated between 100 and 300 K. We observe a sharp drop of the in-plane resistivity at 200K due to the onset of conduction along the Si / SiO2 interface rela...
1406.1282v1
2014-06-20
Anomalous Hall Effect in Ge(1-x-y)Pb(x)Mn(y)Te Composite System
The purpose of this study was to investigate the magnetotransport properties of the Ge(0.743)Pb(0.183)Mn(0.074)Te mixed crystal. The results of magnetization measurements indicated that the compound is a spin-glass-like diluted magnetic semiconductor with critical temperature TSG = 97.5 K. Nanoclusters in the sample ar...
1406.5294v1
2014-07-22
Universal scaling of the critical temperature for thin films near the superconducting-to-insulating transition
Thin superconducting films form a unique platform for geometrically-confined, strongly-interacting electrons. They allow an inherent competition between disorder and superconductivity, which in turn enables the intriguing superconducting-to-insulator transition and believed to facilitate the comprehension of high-Tc su...
1407.5945v2
2014-09-18
Electrical and optical properties of ITO thin films prepared by DC magnetron sputtering for low-emitting coatings
Optimized DC magnetron sputtering system for the deposition of transparent conductive oxides (TCOs), such indium tin oxide (ITO) on glass substrate has been applied in order to achieve low-emitting (low-e) transparent coatings. To obtain the concerned electrical resistance and high infrared reflection, first the effect...
1409.5293v1
2014-09-25
Characterisation of Glass Electrodes and RPC Detectors for $INO-ICAL$ Experiment
India-based Neutrino Observatory (INO) is a planned neutrino experiment to be build up in southern part of India.The INO observatory will host a 51 kton Iron Calorimeter (ICAL) detector to detect atmospheric neutrinos. Resistive Plate Chamber (RPC) has been chosen as the active detector element for the ICAL experiment....
1409.7184v1
2014-11-24
Thermoelectric power of bulk black-phosphorus
The potential of bulk black-phosphorus for thermoelectric applications has been experimentally studied. The Seebeck Coefficient (S) has been measured in the temperature range from 300 K to 385 K, finding a value of S = +335 +- 10 uV/K at room temperature (indicating a naturally occurring p-type conductivity). S increas...
1411.6468v2
2014-11-26
Towards high mobility InSb nanowire devices
We study the low-temperature electron mobility of InSb nanowires. We extract the mobility at 4.2 Kelvin by means of field effect transport measurements using a model consisting of a nanowire-transistor with contact resistances. This model enables an accurate extraction of device parameters, thereby allowing for a syste...
1411.7285v2
2014-12-22
Large anisotropic thermal conductivity of intrinsically two-dimensional metallic oxide PdCoO$_2$
The highly conductive layered metallic oxide \pdcoo{} is a near-perfect analogue to an alkali metal in two dimensions. It is distinguished from other two-dimensional electron systems where the Fermi surface does not reach the Brillouin zone boundary by a high planar electron density exceeding $10^{15}$ cm$^{-2}$. The s...
1412.6919v1
2015-02-06
Anomalous Pressure Dependence of magnetic Ordering Temperature in Tb to 141 GPa: Comparison with Gd and Dy
In previous studies the pressure dependence of the magnetic ordering temperature $T_{\text{o}}$ of Dy was found to exhibit a sharp increase above its volume collapse pressure of 73 GPa, appearing to reach temperatures well above ambient at 157 GPa. In a search for a second such lanthanide, electrical resistivity measur...
1502.01785v1
2015-02-07
Interband Tunneling for Hole Injection in III-Nitride Ultra-violet Emitters
Ultra-violet emitters have several applications in the areas of sensing, water purification, and data storage. While the III-Nitride semiconductor system has the band gap region necessary for ultraviolet emission, achieving efficient ultraviolet solid state emitters remains a challenge due to the low p-type conductivit...
1502.02080v1
2015-02-27
Quantum oscillations, thermoelectric coefficients and the Fermi surface of semi-metallic WTe2
We present a study of angle-resolved quantum oscillations of electric and thermoelectric transport coefficients in semi-metallic WTe$_{2}$, which has the particularity of displaying a large B$^{2}$ magneto-resistance. The Fermi surface consists of two pairs of electron-like and hole-like pockets of equal volumes in a "...
1502.07797v2
2015-05-19
Energy Exchange between Phononic and Electronic Subsystem Governing The Nonlinear Conduction in DCNQI$_2$Cu
We present a dynamical study on the nonlinear conduction behaviour in the commensurate charge-density-wave phase of the quasi-one-dimensional conductor DCNQI$_2$Cu below 75 K. We can accurately simulate magnitude and time-dependence of the measured conductivity in response to large voltage pulses by accounting for the ...
1505.04907v2
2015-08-19
Argument on superconductivity pairing mechanism from cobalt impurity doping in FeSe: spin ($s_{\pm}$) or orbital ($s_{++}$) fluctuation
In high-superconducting transition temperature ($T_{\rm c}$) iron-based superconductors, interband sign reversal ($s_{\rm \pm}$) and sign preserving ($s_{\rm ++}$) $s$-wave superconducting states have been primarily discussed as the plausible superconducting mechanism. We study Co impurity scattering effects on the sup...
1508.04605v2
2015-08-19
Electric field control of spin lifetimes in Nb-SrTiO$_3$ by spin-orbit fields
We show electric field control of the spin accumulation at the interface of the oxide semiconductor Nb-SrTiO$_{3}$ with Co/AlO$_{x}$ spin injection contacts at room temperature. The in-plane spin lifetime $\tau_\parallel$ as well as the ratio of the out-of-plane to in-plane spin lifetime $\tau_\perp/\tau_\parallel$ is ...
1508.04649v1
2015-09-13
Effects of Cr substitution on the magnetic and transport properties and electronic states of SrRuO3 epitaxial thin films
The effect of Cr substitution in a SrRuO3 epitaxial thin film on SrTiO3 substrate was investigated by measuring the magnetic and transport properties and the electronic states. The ferromagnetic transition temperature of the SrRu0.9Cr0.1O3 film (166 K) was higher than that of the SrRuO3 film (147 K). Resonant photoemis...
1509.03804v1
2015-10-22
Anomalous transport and thermoelectric performances of CuAgSe compounds
The copper silver selenide has two phases: the low-temperature semimetal phase ({\alpha}-CuAgSe) and high-temperature phonon-glass superionic phase (\b{eta}-CuAgSe). In this work, the electric transport and thermoelectric properties of the two phases are investigated. It is revealed that the \b{eta}-CuAgSe is a p-type ...
1510.06616v1
2015-11-12
Experimental and numerical analysis of tribological behavior of CrAl(Si)N films during Scratch
Scratch sliding tests with a ZrO2 ball and CrAlSiN films with different Si content were conducted due to CrAlSiN films having high hardness and good wear resistance. After up to 6000 cycles the specimens were analyzed by Scanning Electron Microscopy. The friction coefficient of CrAlSiN was lower than that of CrAlN film...
1511.04092v2
2015-12-27
Room-temperature paramagnetoelectric effect in magnetoelectric multiferroics Pb(Fe1/2Nb1/2)O3 and its solid solution with PbTiO3
We have observed the magnetoelectric response at room temperature and above in high-resistive ceramics made of multiferroic Pb(Fe1/2Nb1/2)O3 (PFN) and PFN-based solid solution 0.91PFN-0.09PbTiO3 (PFN-PT). The value of the paramagnetoelectric (PME) coefficient shows a pronounced maximum near the ferroelectric-to-paraele...
1512.08217v1
2015-12-31
Intrinsic Nanotwin Effect on Thermal Boundary Conductance in Bulk and Single-Nanowire Twinning Superlattices
Coherent twin boundaries form periodic lamellar twinning in a wide variety of semiconductor nanowires, and are often viewed as near-perfect interfaces with reduced phonon and electron scattering behaviors. Such unique characteristics are of practical interest for high-performance thermoelectrics and optoelectronics; ho...
1512.09357v2
2016-02-20
Investigation of the electron-phonon interaction in $N{{b}_{3}}Sn$ with the aid of microcontacts
The method of microcontact spectroscopy in the superconducting state was used to investigate weak nonlinearities of the current-voltage characteristics of point contacts made of $N{{b}_{3}}Sn$ single crystals. The nature of the spectrum of the electron-phonon interaction was found to vary considerably from contact to c...
1602.06398v1
2016-04-11
Single crystal growth of CeTAl$_3$ (T = Cu, Ag, Au, Pd and Pt)
We report single crystal growth of the series of CeTAl$_3$ compounds with T = Cu, Ag, Au, Pd and Pt by means of optical float zoning. High crystalline quality was confirmed in a thorough characterization process. With the exception of CeAgAl$_3$, all compounds crystallize in the non-centrosymmetric tetragonal BaNiSn$_{...
1604.03146v1
2016-04-14
Large magnetothermopower and Fermi surface reconstruction in Sb$_2$Te$_2$Se
We report the magnetoresistance, magnetothermopower and quantum oscillation study of Sb$_2$Te$_2$Se single crystal. The in-plane transverse magnetoresistance exhibits a crossover at a critical field $B^*$ from semiclassical weak-field $B^2$ dependence to the high-field unsaturated linear magnetoresistance which persist...
1604.04281v1
2016-04-15
Electronic Structure Descriptor for Discovery of Narrow-Band Red-Emitting Phosphors
Narrow-band red-emitting phosphors are a critical component in phosphor-converted light-emitting diodes for highly efficient illumination-grade lighting. In this work, we report the discovery of a quantitative descriptor for narrow-band Eu2+-activated emission identified through a comparison of the electronic structure...
1604.04581v1
2016-04-18
Superconductivity in undoped CaFe2As2 single crystals
Single crystals of undoped CaFe2As2 were grown by a FeAs self-flux method, and the crystals were quenched in ice-water rapidly after high temperature growth. The quenched crystal undergoes a collapsed tetragonal structural phase transition around 80 K revealed by the temperature dependent X-ray diffraction measurements...
1604.04964v1
2016-04-22
Multiband behavior and non-metallic low-temperature state of K$_{0.50}$Na$_{0.24}$Fe$_{1.52}$Se$_{2}$
We report evidence for multiband transport and an insulating low-temperature normal state in superconducting K$_{0.50}$Na$_{0.24}$Fe$_{1.52}$Se$_{2}$ with $T_{c}\approx 20$ K. The temperature-dependent upper critical field, $H_{c2}$, is well described by a two-band BCS model. The normal-state resistance, accessible at ...
1604.06793v1
2016-05-30
High-field electron transport in bulk ZnO
Current-voltage dependence is measured in (Ga,Sb)-doped ZnO up to 150 kV/cm electric fields. A channel temperature is controlled by applying relatively short (few ns) voltage pulses to two-terminal samples. The dependence of electron drift velocity on electron density ranging from 1.42$\times$10$^{17}$ cm$^{-3}$ to 1.3...
1605.09117v1
2016-06-27
Hafnium carbide formation in oxygen deficient hafnium oxide thin films
On highly oxygen deficient thin films of hafnium oxide (hafnia, HfO$_{2-x}$) contaminated with adsorbates of carbon oxides, the formation of hafnium carbide (HfC$_x$) at the surface during vacuum annealing at temperatures as low as 600 {\deg}C is reported. Using X-ray photoelectron spectroscopy the evolution of the HfC...
1606.08227v1
2016-06-29
Improved model for the thermal conductivity of binary metallic systems
We extended and corrected Mott's two-band model for the composition-dependence of thermal and electrical conductivity in binary metal alloys based on high-throughput time-domain thermoreflectance (TDTR) measurements on diffusion multiples and scatterer-density calculations from first principles. Examining PdAg, PtRh, A...
1606.09287v2
2016-06-30
Superconductivity at 5.5 K in Nb2PdSe5 compound
We report superconductivity in as synthesized Nb2PdSe5, which is similar to recently discovered Nb2PdS5 compound having very high upper critical field, clearly above the Pauli paramagnetic limit [Sci. Rep. 3, 1446 (2013)]. A bulk polycrystalline Nb2PdSe5 sample is synthesized by solid state reaction route in phase pure...
1606.09369v2
2016-08-01
Phase Transition in IrTe$_2$ induced by spin-orbit coupling
IrTe$_2$ has been renewed as an interesting system showing competing phenomenon between a questionable density-wave transition near 270 K followed by superconductivity with doping of high atomic number materials. Higher atomic numbers of Te and Ir supports strong spin-orbital coupling in this system. Using dynamical me...
1608.00467v1
2016-08-03
Edge-induced Schottky barrier modulation at metal contacts to exfoliated molybdenum disulfide flakes
Ultrathin two-dimensional semiconductors obtained from layered transition-metal dichalcogenides such as molybdenum disulfide (MoS2) are promising for ultimately scaled transistors beyond Si. Although the shortening of the semiconductor channel is widely studied, the narrowing of the channel, which should also be import...
1608.01061v1
2016-08-23
Chiral anomaly and longitudinal magnetotransport in type-II Weyl semimetals
In the presence of parallel electric and magnetic fields, the violation of separate number conservation laws for the three dimensional left and right handed Weyl fermions is known as the chiral anomaly. The recent discovery of Weyl and Dirac semimetals has paved the way for experimentally testing the effects of chiral ...
1608.06625v2
2016-10-19
Anomalous Thermal Diffusivity in Underdoped YBa$_2$Cu$_3$O$_{6+x}$
We present local optical measurements of thermal diffusivity in the $ab$ plane of underdoped YBCO crystals. We find that the diffusivity anisotropy is comparable to reported values of the electrical resistivity anisotropy, suggesting that the anisotropies have the same origin. The anisotropy drops sharply below the cha...
1610.05845v2
2016-10-22
High performance THz emitters based on ferromagnetic/nonmagnetic heterostructures
We report a THz emitter with excellent performances based on nonmagnetic (NM) and ferromagnetic (FM) heterostructures. The spin currents are first excited by the femtosecond laser beam in the NM/FM bilayer, and then transient charge currents are generated by inverse spin Hall effect, leading to THz emission out of the ...
1610.07020v1
2016-10-26
S2DS: Physics-Based Compact Model for Circuit Simulation of Two-Dimensional Semiconductor Devices Including Non-Idealities
We present a physics-based compact model for two-dimensional (2D) field-effect transistors (FETs) based on monolayer semiconductors such as MoS2. A semi-classical transport approach is appropriate for the 2D channel, enabling simplified analytical expressions for the drain current. In addition to intrinsic FET behavior...
1610.08489v2
2016-11-14
Nonlinear Transport of Graphene in the Quantum Hall Regime
We have studied the breakdown of the integer quantum Hall (QH) effect with fully broken symmetry, in an ultra-high mobility graphene device sandwiched between two single crystal hexagonal boron nitride substrates. The evolution and stabilities of the QH states are studied quantitatively through the nonlinear transport ...
1611.04221v1
2016-11-15
Encapsulated Nanowires: Boosting Electronic Transport in Carbon Nanotubes
The electrical conductivity of metallic carbon nanotubes (CNTs) quickly saturates with respect to bias voltage due to scattering from a large population of optical phonons. Decay of these dominant scatterers in pristine CNTs is too slow to offset an increased generation rate at high voltage bias. We demonstrate from fi...
1611.04867v2
2016-12-06
Enhanced Structural Stability and Photo Responsiveness of CH3NH3SnI3 Perovskite via Pressure-Induced Amorphization and Recrystallization
An organic-inorganic halide perovskite of CH3NH3SnI3 with significantly improved structural stability is obtained via pressure-induced amorphization and recrystallization. In situ high-pressure resistance measurements reveal an increased electrical conductivity by 300% in the pressure-treated perovskite. Photocurrent m...
1612.01649v1
2016-12-20
Enhanced Superconductivity in TiO Epitaxial Thin Films
Titanium oxides have many fascinating optical and electrical properties, such as the superconductivity at 2.0 K in cubic titanium monoxide TiO polycrystalline bulk. However, the lack of TiO single crystals or epitaxial films has prevented systematic investigations on its superconductivity. Here, we report the basic sup...
1612.06506v1
2017-02-02
Two-temperature equations of state for d-band metals irradiated by femtosecond laser pulses
The cold curves for energy and pressure of Copper, Iron, and Tantalum were obtained using methods of the density functional theory. We consider hydrostatic and uniaxial deformations in the range from double compression of the initial volume per atom to double stretching. The presence of allotropic transformation from $...
1702.00825v3
2017-02-15
New bulk p-type skutterudites DD0.7Fe2.7Co1.3Sb12-xXx (X = Ge, Sn) reaching ZT>1.3
The best p-type skutterudites so far are didymium filled, Fe/Co substituted, Sb-based skutterudites. Substitution at the Sb-sites influences the electronic structure, deforms the Sb4-rings, enhances the scattering of phonons on electrons and impurities and this way reduces the lattice thermal conductivity. In this pape...
1702.04498v1
2017-02-24
Out-of-plane easy-axis in thin films of diluted magnetic semiconductor Ba1-xKx(Zn1-yMny)2As2
Single-phased, single-oriented thin films of Mn-doped ZnAs-based diluted magnetic semiconductor (DMS) Ba1-xKx(Zn1-yMny)2As2 (x = 0.03, 0.08; y = 0.15) have been deposited on Si, SrTiO3, LaAlO3, (La,Sr)(Al,Ta)O3, and MgAl2O4 substrates, respectively. Utilizing a combined synthesis and characterization system excluding t...
1702.07506v1
2017-06-16
An argon ion beam milling process for native $\text{AlO}_\text{x}$ layers enabling coherent superconducting contacts
We present an argon ion beam milling process to remove the native oxide layer forming on aluminum thin films due to their exposure to atmosphere in between lithographic steps. Our cleaning process is readily integrable with conventional fabrication of Josephson junction quantum circuits. From measurements of the intern...
1706.06424v1
2017-06-29
Magnetotransport properties of MoP$_2$
We report magnetotransport and de Haas-van Alphen (dHvA) effect studies on MoP$_2$ single crystals, predicted to be type-2 Weyl semimetal with four pairs of robust Weyl points located below the Fermi level and long Fermi arcs. The temperature dependence of resistivity shows a peak before saturation, which does not move...
1706.09830v1
2017-09-11
Massive fermions with low mobility in antiferromagnet orthorhombic CuMnAs single crystals
We report the physical properties of orthorhombic o-CuMnAs single crystal, which is predicted to be a topological Dirac semimetal with magnetic ground state and inversion symmetry broken. o-CuMnAs exhibits an antiferromagnetic transition with TN ~ 312 K. Further characterizations of magnetic properties suggest that the...
1709.03394v2
2017-09-13
Ultra-broadband photodetectors based on epitaxial graphene quantum dots
Graphene is an ideal material for hot-electron bolometers, due to its low heat capacity and weak electron-phonon coupling. Nanostructuring graphene with quantum dot constrictions yields detectors with extraordinarily high intrinsic responsivity, higher than 1x10^9 V/W at 3K. The sensing mechanism is bolometric in natur...
1709.04498v1
2017-09-27
Pressure-induced Lifshitz transition in NbP: Raman, x-ray diffraction, electrical transport and density functional theory
We report high pressure Raman, synchrotron x-ray diffraction and electrical transport studies on Weyl semimetals NbP and TaP along with first-principles density functional theoretical (DFT) analysis. The frequencies of first-order Raman modes of NbP harden with increasing pressure and exhibit a slope change at P$_c$ $\...
1709.09368v1
2017-10-27
Unusual behavior of cuprates explained by heterogeneous charge localization
The cuprate high-temperature superconductors are among the most intensively studied materials, yet essential questions regarding their principal phases and the transitions between them remain unanswered. Generally thought of as doped charge-transfer insulators, these complex lamellar oxides exhibit pseudogap, strange-m...
1710.10221v1
2017-11-05
Investigations of a Robotic Testbed with Viscoelastic Liquid Cooled Actuators
We design, build, and thoroughly test a new type of actuator dubbed viscoelastic liquid cooled actuator (VLCA) for robotic applications. VLCAs excel in the following five critical axes of performance: energy efficiency, torque density, impact resistence, joint position and force controllability. We first study the desi...
1711.01649v2
2017-11-07
Epitaxial stabilization of pulsed laser deposited Sr$_{n+1}$Ir$_n$O$_{3n+1}$ thin films: entangled effect of growth dynamics and strain
The subtle balance of electronic correlations, crystal field splitting and spin--orbit coupling in layered Ir$^{4+}$ oxides can give rise to novel electronic and magnetic phases. Experimental progress in this field relies on the synthesis of epitaxial films of these oxides. However, the growth of layered iridates with ...
1711.02767v3
2017-11-09
Magnetic phase separation and strong AFM nature of hexagonal Gd$_5$Sb$_3$
We report on the combined results of structural, magnetic, transport and calorimetric properties of Mn$_5$Si$_3$-type hexagonal Gd$_5$Sb$_3$. With decreasing temperature, it exhibits a ferromagnetic-like transition at 265 K, N\'{e}el transition at 95.5 K and a spin-orientation transition at 62 K. The system is found to...
1711.03263v1
2017-11-29
Pressure-induced ferromagnetism due to an anisotropic electronic topological transition in Fe1.08Te
A rapid and anisotropic modification of the Fermi-surface shape can be associated with abrupt changes in crystalline lattice geometry or in the magnetic state of a material. In this study we show that such an electronic topological transition is at the basis of the formation of an unusual pressure-induced tetragonal fe...
1711.10745v1
2018-01-15
Improving Graphene-metal Contacts: Thermal Induced Polishing
Graphene is a very promising material for nanoelectronics applications due to its unique and remarkable electronic and thermal properties. However, when deposited on metallic electrodes the overall thermal conductivity is significantly decreased. This phenomenon has been attributed to the mismatch between the interface...
1801.04785v1
2018-01-31
Commensurability Oscillations in One-Dimensional Graphene Superlattices
We report the experimental observation of commensurability oscillations (COs) in 1D graphene superlattices. The widely tunable periodic potential modulation in hBN encapsulated graphene is generated via the interplay of nanopatterned few layer graphene acting as a local bottom gate and a global Si back gate. The longit...
1802.00016v2
2018-03-22
High density carriers at a strongly coupled graphene-topological insulator interface
We report on a strongly coupled bilayer graphene (BLG) - \bise\ device with a junction resistance of less than 1.5 k$\Omega\mu$m$^2$. This device exhibits unique behavior at the interface, which cannot be attributed to either material in absence of the other. We observe quantum oscillations in the magnetoresistance of ...
1803.08260v1
2018-03-27
Large-Scale Fabrication of RF MOSFETs on Liquid-Exfoliated MoS2
For the first time, thousands of RF MOSFETs were batch-fabricated on liquid-exfoliated MoS2 below 300 {\deg}C with nearly 100% yield. The large-scale fabrication with high yield allowed the average performance instead of the best performance to be reported. The DC performance of these devices were typical, but the RF p...
1803.09906v1
2018-05-20
Autonomous actuation of zero modes in mechanical networks far from equilibrium
A zero mode, or floppy mode, is a non-trivial coupling of mechanical components yielding a degree of freedom with no resistance to deformation. Engineered zero modes have the potential to act as microscopic motors or memory devices, but this requires an internal actuation mechanism that can overcome unwanted fluctuatio...
1805.07728v2
2018-06-06
Pressure Evolution of Magnetism in URhGa
In this paper, we report the results of an ambient and high pressure study of a 5f-electron ferromagnet URhGa. The work is focused on measurements of magnetic and thermodynamic properties of a single crystal sample and on the construction of the p-T phase diagram. Diamond anvil cells were employed to measure the magnet...
1806.02686v1
2018-06-25
Ferromagnetism above 1000 K in highly cation-ordered double-perovskite insulator Sr3OsO6
Magnetic insulators have been intensively studied for over 100 years, and they, in particular ferrites, are considered to be the cradle of magnetic exchange interactions in solids. Their wide range of applications include microwave devices and permanent magnets . They are also suitable for spintronic devices owing to t...
1806.09308v1