Pressure evolution of electrical transport in the 3D topological insulator (Bi,Sb)[subscript 2] (Se,Te)[subscript 3]
Abstract not provided
Jeffries, J. R.↗
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Theory of spin-coherent electrical transport through a defect spin state in a metal/insulator/ferromagnet tunnel junction undergoing ferromagnetic resonance
In this work, we describe the coherent dynamics of electrical transport through a localized spin-dependent state, such as is associated with a defect spin, at the interface of a ferromagnet and a nonmagnetic material during ferromagnetic resonance. As the ferromagnet magnetic moment precesses, charge carriers are dynamically spin filtered by the localized state, leading to a dynamic spin accumulation on the defect. Local effective magnetic fields modify the precession of a spin on the defect, which also modifies the time-integrated total charge current through the defect. Lastly, we thus identify a form of current-detected spin resonance that reveals the local magnetic environment of a carrier spin located at a defect, and thus potentially the defect’s identity.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Quantifying the hydrodynamic contribution to electrical transport in non-Brownian suspensions
Electrical transport in semiconducting and metallic particle suspensions is an enabling feature of emerging grid-scale battery technologies. Although the physics of the transport process plays a key role in these technologies, no universal framework has yet emerged. Here, we examine the important contribution of shear flow to the electrical transport of non-Brownian suspensions. We find that these suspensions exhibit a strong dependence of the transport rate on the particle volume fraction and applied shear rate, which enables the conductivity to be dynamically changed by over 10 7 decades based on the applied shear rate. We combine experiments and simulations to conclude that the transport process relies on a combination of charge and particle diffusion with a rate that can be predicted using a quantitative physical model that incorporates the self-diffusion of the particles.
42 ENGINEERING↗
Challenges and Opportunities of Grid Modernization and Electric Transportation
Grid investments that support electric vehicle deployments as a part of planned modernization efforts can enable a more efficient and cost-effective transition to electric transportation and allow investor-owned electric companies and public power companies to realize new revenue resources in times of flat or declining loads. This paper discusses the challenges and opportunities associated with an increase in plug-in electric vehicle (PEV) adoption and how working together both sectors stand to benefit from closer integration.
24 POWER TRANSMISSION AND DISTRIBUTION↗
Structural and electrical transport studies on CrN(001) thin films
We report the structural and electrical transport studies on CrN{sub 1-x} (CrN) thin films with varying of N{sub 2} flow (5 – 25 SCCM) in an Argon environment of 25 SCCM. CrN thin films were grown at 600°C, in a multi chamber vacuum system at working pressure of 1×10{sup −2} Torr, under the base pressure of 1×10{sup −7} Torr. Structural and electrical transport measurements were carried out using X-ray diffraction (XRD), atomic force microscopy (AFM) and SQUID magnetometer, respectively. XRD (θ-2θ, ω-2θ, and ω) patterns on CrN thin films revealed a structural phase transition which is associated with the lattice parameter variation from 4.136 to 4.168 Å. The temperature dependent resistivity measurements on CrN/MgO(001) showed a clear change in slope at ≈280 K which confirms the magneto-structural transition of CrN from paramagnetic rock salt face-centered-cubic (FCC) to antiferromagnetic orthorhombic structure.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Baseline tests of the Volkswagen transporter electric delivery van
The Volkswagen Transporter, an electric delivery van, was tested as part of an Energy Research and Development Administration (ERDA) project to characterize the state of the art of electric vehicles. The Volkswagen Transporter is a standard Volkswagen van that has been converted to an electric vehicle. It is powered by a 144-volt traction battery. A direct current (dc) chopper controller, actuated by a conventional accelerator pedal, regulates the voltage or power applied to the 16-kilowatt (21-hp) motor. The braking system uses conventional hydraulic braking in combination with an electric regenerative braking system. The Volkswagen vehicle performance test results are presented.
Soltis, R. F.↗
AC electrical transport detection of magnetic properties of small, granular, and heterogeneous samples
Experimental constraints and sample limitations can preclude ideal measurements of electrical transport properties of materials. In such situations, AC electrical transport methods are often employed due to a significant increase in signal-to-noise ratio they can provide. However, dynamic effects that are not often accounted for may be present that may modify the signals in these measurements. In particular, dynamic filtering effects are prominent in small, granular, and heterogeneous materials. We demonstrate that a lock-in amplifier based circuit can distinguish between these DC transport and AC filtering effects. Here, we further demonstrate that this filtering can reveal distinct signatures of magnetic transitions while providing a measure of sample quality.
47 OTHER INSTRUMENTATION↗
Electric transport coefficients in highly epitaxial LaBaCo{sub 2}O{sub 5 + δ} films with “p-to-n” transition induced by oxygen deficiency
Electric transport coefficients such as carrier type, density, and mobility are the important physical parameters in designing functional devices. In this work, we report the study on the electric transport coefficients of the highly epitaxial LaBaCo{sub 2}O{sub 5 + δ} (LBCO) films, which were discussed as a function of electric conductivity for the first time and compared with the results calculated by the theory for mixed conduction. The mobility in the LBCO films was determined to be ∼0.85 and ∼40 cm{sup 2}/V s for holes and electrons, respectively, and the density of p-type carriers strongly depends on the oxygen deficiency. Solid evidence is presented to demonstrate that the oxygen deficiency cannot make LBCO materials changed from p- to n-type. The n-type conduction observed in experiment is a counterfeit phenomenon caused by the deficiency in Hall measurement, rather than a realistic transition induced by oxygen deficiency. In addition, the temperature-dependent conductivity was discussed using the differential coefficients, which might be useful in the study of the samples with magnetic transition.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Influence of deep levels on the electrical transport properties of CdZnTeSe detectors
Here, we investigated the influence of deep levels on the electrical transport properties of CdZnTeSe radiation detectors by comparing experimental data with numerical simulations based on the simultaneous solution of drift-diffusion and Posisson equations, including the Shockley-Read-Hall model of the carrier trapping. We determined the Schottky barrier heights and the Fermi level position from I-V measurements. We measured the time evolution of the electric field and the electrical current after the application of a voltage bias. We observed that the electrical properties of CZTS are fundamentally governed by two deep levels close to the mid-bandgap - one recombination and one hole trap. We show that the hole trap indirectly increases the mobility-lifetime product of electrons. We conclude that the structure of deep levels in CZTS are favorable for high electrical charge transport.
36 MATERIALS SCIENCE↗
Effect of sintering temperature on structural, magnetic and electrical transport properties of La0.67Ca0.33MnO3 ceramics prepared by Plasma Activated Sintering
Highlights: • La{sub 0.67}Ca{sub 0.33}MnO{sub 3} were prepared by using Plasma Activated Sintering technology. • Detailed studies of sintering temperature effect on structural, magnetic and electrical transport behaviors were investigated. • The observed behaviors have been explained by oxygen vacancy effect in combination with grain size effect. - Abstract: La{sub 0.67}Ca{sub 0.33}MnO{sub 3} (LCMO) ceramics were prepared by Plasma Activated Sintering (PAS). The effect of sintering temperature on structural, magnetic and electrical transport properties of the LCMO ceramics were investigated. XRD and SEM characterizations of the LCMO ceramics indicated that all samples exhibited single orthorhombic phase. Also, through PAS dense LCMO ceramics were obtained. Certain interesting phenomena were observed from the PAS sintering temperature effect on the magnetic and transport behaviors of LCMO ceramics, which were significantly different from traditional sintering methods The magnetization decreased and the resistivity increased as the sintering temperature increased, whereas the T{sub C} and T{sub IM} shifted towards the lower temperature side. The conduction mechanism of all samples was electron-magnon scattering process in the ferromagnetic low-temperature region, while the paramagnetic high-temperature region mechanism was explained with the variable range hopping (VRH) model. All these behaviors were explained through the oxygen vacancy effect in combination with the grain size effect.
36 MATERIALS SCIENCE↗
Substrate-dependent post-annealing effects on the strain state and electrical transport of epitaxial La{sub 5/8-y}Pr{sub y}Ca{sub 3/8}MnO{sub 3} films
Large scale electronic phase separation (EPS) between ferromagnetic metallic and charge-ordered insulating phases in La{sub 5/8-y}Pr{sub y}Ca{sub 3/8}MnO{sub 3} (y = 0.3) (LPCMO) is very sensitive to the structural changes. This work investigates the effects of post-annealing on the strain states and electrical transport properties of LPCMO films epitaxially grown on (001){sub pc} SrTiO{sub 3} (tensile strain), LaAlO{sub 3} (compressive strain) and NdGaO{sub 3} (near-zero strain) substrates. Before annealing, all the films are coherent-epitaxial and insulating through the measured temperature range. Obvious change of film lattice is observed during the post-annealing: the in-plane strain in LPCMO/LAO varies from −1.5% to −0.1% while that in LPCMO/STO changes from 1.6% to 1.3%, and the lattice of LPCMO/NGO keeps constant because of the good lattice-match between LPCMO and NGO. Consequently, the varied film strain leads to the emergence of metal-insulator transitions (MIT) and shift of the critical transition temperature in the electrical transport. These results demonstrate that lattice-mismatch combined with post-annealing is an effective approach to tune strain in epitaxial LPCMO films, and thus to control the EPS and MIT in the films.
36 MATERIALS SCIENCE↗
The influence of hydrogen on the chemical, mechanical, optical/electronic, and electrical transport properties of amorphous hydrogenated boron carbide
Because of its high electrical resistivity, low dielectric constant (κ), high thermal neutron capture cross section, and robust chemical, thermal, and mechanical properties, amorphous hydrogenated boron carbide (a-B{sub x}C:H{sub y}) has garnered interest as a material for low-κ dielectric and solid-state neutron detection applications. Herein, we investigate the relationships between chemical structure (atomic concentration B, C, H, and O), physical/mechanical properties (density, porosity, hardness, and Young's modulus), electronic structure [band gap, Urbach energy (E{sub U}), and Tauc parameter (B{sup 1/2})], optical/dielectric properties (frequency-dependent dielectric constant), and electrical transport properties (resistivity and leakage current) through the analysis of a large series of a-B{sub x}C:H{sub y} thin films grown by plasma-enhanced chemical vapor deposition from ortho-carborane. The resulting films exhibit a wide range of properties including H concentration from 10% to 45%, density from 0.9 to 2.3 g/cm{sup 3}, Young's modulus from 10 to 340 GPa, band gap from 1.7 to 3.8 eV, Urbach energy from 0.1 to 0.7 eV, dielectric constant from 3.1 to 7.6, and electrical resistivity from 10{sup 10} to 10{sup 15} Ω cm. Hydrogen concentration is found to correlate directly with thin-film density, and both are used to map and explain the other material properties. Hardness and Young's modulus exhibit a direct power law relationship with density above ∼1.3 g/cm{sup 3} (or below ∼35% H), below which they plateau, providing evidence for a rigidity percolation threshold. An increase in band gap and decrease in dielectric constant with increasing H concentration are explained by a decrease in network connectivity as well as mass/electron density. An increase in disorder, as measured by the parameters E{sub U} and B{sup 1/2}, with increasing H concentration is explained by the release of strain in the network and associated decrease in structural disorder. All of these correlations in a-B{sub x}C:H{sub y} are found to be very similar to those observed in amorphous hydrogenated silicon (a-Si:H), which suggests parallels between the influence of hydrogenation on their material properties and possible avenues for optimization. Finally, an increase in electrical resistivity with increasing H at <35 at. % H concentration is explained, not by disorder as in a-Si:H, but rather by a lower rate of hopping associated with a lower density of sites, assuming a variable range hopping mechanism interpreted in the framework of percolation theory.
36 MATERIALS SCIENCE↗
Low temperature magnetic and electrical transport behavior of Co{sub 58.5}Ga{sub 41.5} alloy
The electrical transport and magnetic properties of Co{sub 58.5}Ga{sub 41.5} binary alloy have been investigated in the temperature range 2-300 K. Analysis of field and temperatures dependence magnetization data suggests a reentrant magnetic behavior with Curie temperature (T{sub C}) ∼90 K. Temperature dependence of resistivity shows large residual resistivity values which is sensitive to the applied magnetic field. The temperature and field dependent resistivity behavior indicates the presence of spin fluctuations at low temperature. Magnetoresistance (MR) of 17 % has been observed at 2 K in 90 kOe field, which follows a power law with exponent varying form 0.5 at low temperature to linear behavior at higher temperature. The temperature variation of magnetization and MR can be understood on the basis of ferromagnetic matrix with finite spin clusters.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Nonlinear electrical transport near the metal–insulator transition in V 4 O 7 thin films
Nonlinear electrical transport associated with correlated electronic states has been widely investigated in transition-metal oxides near metal–insulator transitions. Here, in this study, we investigate nonlinear transport and threshold switching in sputter-deposited V 4 O 7 thin films grown on fused silica substrates. Temperature-dependent transport measurements show a metal–insulator transition near 240 K with negligible thermal hysteresis, defining the temperature scale that governs the nonlinear electrical response. Current–voltage measurements reveal reproducible bipolar threshold switching over a broad temperature range, with the threshold voltage decreasing systematically as the transition temperature is approached. Electrothermal finite-element simulations reproduce the measured switching characteristics and show that switching occurs when localized Joule heating drives a confined region of the device toward the transition temperature. The simulated peak local temperature at threshold lies close to the intrinsic metal–insulator transition temperature of V 4 O 7 , establishing that the nonlinear electrical response originates from electrothermal feedback acting on the strongly temperature-dependent conductivity near the transition. These results identify V 4 O 7 thin films as a model correlated-oxide system in which volatile threshold switching emerges from proximity to an extended metal–insulator transition.
25 ENERGY STORAGE↗
Thermal and electrical transport in a tungsten crystal for strong magnetic fields and low temperatures
Thermal and electrical transport in tungsten crystal for strong magnetic fields and liquid helium temperatures
Long, J. R.↗