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We study spin transport through graphene-like substrates in the presence of one or several, locally induced spin–orbit coupling (SOC) terms resulting from periodically placed strips, on their top and decorated with a random distribution of impurities. Intrinsic SOC, Rashba SOC and/or pseudo-spin-inversion-asymmetry coupling are considered. A systematic investigation of the spin conductance identifies the main SOC terms which lead to its energy dependence as well as the extent to which the impurity concentration and each SOC term can affect or tune it, In addition, the spin current flow is considered in the presence of different SOC impurities and their related group symmetry such C 6 v , C 3 v , D 6 h and D 3 h . Further, we show that the quantum spin-Hall effect (QSHE) related to the spin edge states depends only on the spin character when the PIA and ISO terms are not sublattice resolved, and on both the spin and sublattice character when they are. In addition, we show that the RSO term plays a major role in obtaining edge states that are either protected on both edges or only on one edge against backscattering. This Rashba term creates an anticrosing gap that affects the symmetry in the edge localizations and leads to half-topological states. The results can facilitate the experimental choice of appropriately decorated strips to (i) develop spin-transistor devices by tuning the Fermi energy, (ii) control the robustness of the QSHE against backscattering even in the presence of on-site sublattice asymmetry induced by a transverse electric field or functionalizations, and (iii) provide a strong theoretical support for spintronic quantum devices. [ABSTRACT FROM AUTHOR]

Transport properties of dense quark matter are discussed in the strong magnetic field, B. B dependence as well as density dependence of the Hall conductivity is discussed, based on the microscopic Kubo formula. We took into account the possibility of the inhomogeneous chiral phase at moderate densities, where anomalous Hall effect is intrinsic and resembles the one in Weyl semimetals in condensed matter physics. Some theoretical aspects inherent in anomalous Hall effect are also discussed.

A comprehensive magnetotransport study on a p‐type single crystal of SnTe topological crystalline insulator is reported, across the cubic‐to‐rhombohedral (R3m) transition at Ts ≈64 K. SnTe exhibits a large unsaturated linear magnetoresistance (LMR) reaching a value of 42% at 5 K and 8 T for (100) plane. LMR is found to have a direct dependence on the mobility and a detailed analysis shows that it follows the classical Parish‐Littlewood model of conductivity fluctuations arising from macroscopic inhomogeneities of tellurium interstitial atoms. Profound SdH oscillations having a π Berry phase are observed in the rhombohedral (R3m) phase having significantly lower carrier density ≈5.32 × 1011 cm−2 at 2 K, which provides direct evidence of protected topological surface states in the R3m phase. The Hall conductivity shows a transformation from one band to two‐band behavior across the structural transition, thus providing an experimental evidence for the degeneracy lifting of bulk valence bands below the cubic symmetry breaking point which is consistent with recent band structure calculations. The overall results indicate that magnetotransport studies can distinctly probe the surface and bulk sensitive properties of SnTe, and can also track the band‐splitting of degenerate bands across the cubic‐to‐rhombohedral (R3m) transition. [ABSTRACT FROM AUTHOR]

Auroral substorm onset locations are highly unpredictable. Previous studies have shown that the By component of the interplanetary magnetic field (IMF) explains ∼5% of the variation in onset magnetic local time (MLT), while solar wind conditions and the other IMF components have even less explanatory power. In this study, we show that the level of geomagnetic activity before substorm onset, as indicated by the AL index, explains an additional ∼5% of the variation in onset MLT. We discuss our results with regard to recent modeling studies, which show that gradients in the ionospheric Hall conductance can lead to a duskward shift of the magnetotail dynamics. Our findings suggest that this magnetosphere‐ionosphere coupling effect may also influence the location of substorm onsets. Plain Language Summary: Substorms are explosive disturbances in our magnetotail that impact the earth's ionosphere. They happen on average several times per day and as a result of this phenomenon, we can see the marvelous aurora. Substorms happen on the nightside of the earth and can take place over a wide range of latitudes and longitudes. In this study, we show that substorms tend to begin at earlier local times during geomagnetically active times than during quiet times. We interpret this tendency as a sign that ionospheric conditions may play a role in determining where substorms occur. Key Points: Ionospheric conditions before substorm onset are different for substorms with an early local time onset versus late local time onsetSubstorm onsets tend to move to earlier local times with increasing geomagnetic activityWe suggest that higher ionospheric conductance leads to a duskward shift in magnetospheric substorm activity [ABSTRACT FROM AUTHOR]

Many minerals have semiconductor properties. It is known that petroleum reservoir rocks permeated with hydrocarbon fluids can sometimes behave as semiconductors. In the Earth’s magnetic field, the electrical conductivity of such materials becomes anisotropic, and the Hall effect is quite possible in rocks in natural conditions and detectable by magnetotelluric sounding. In the anisotropic medium, the field is subject to normal mode splitting, and its components show different attenuation coefficients and phase velocities. The modes differ due to polarization and rotation of the field vectors (clockwise in one mode, and counterclockwise in another). With account of the Hall effect, responses of the medium can be different when the medium is excited by a single normal wave. To detect the Hall effect in MTS surveys, we use the polarization analysis method and select the spectra of modes with right and left circular polarization. Special experiments were carried out to detect the contribution of the Hall effect during the MTS surveys. This article presents the first estimates of the Hall conductivity for the studied rocks.

Y-shaped Kekulé bond textures in a honeycomb lattice on a graphene-copper superlattice have recently been experimentally revealed. In this paper, the effects of such a bond modulation on the transport coefficients of Kekulé-patterned graphene are investigated in the presence of a perpendicular magnetic field. Analytical expressions are derived for the Hall and longitudinal conductivities using the Kubo formula. It is found that the Y-shaped Kekulé bond texture lifts the valley degeneracy of all Landau levels except that of the zero mode, leading to additional plateaus in the Hall conductivity accompanied by a split of the corresponding peaks in the longitudinal conductivity. Consequently, the Hall conductivity is quantized as ± ne 2/ h for n = 2, 4, 6, 8, 10, …, excluding some plateaus that disappear due to the complete overlap of the Landau levels of different cones. These results also suggest that DC Hall conductivity measurements will allow us to determine the Kekulé bond texture amplitude. [ABSTRACT FROM AUTHOR]

We discuss the non-equilibrium dynamics of condensed matter/quantum field systems in the framework of Keldysh technique. In order to deal with the inhomogeneous systems we use the Wigner-Weyl formalism. Unification of the mentioned two approaches is demonstrated on the example of Hall conductivity. We express Hall conductivity through the Wigner transformed two-point Green's functions. We demonstrate how this expression is reduced to the topological number in thermal equilibrium at zero temperature. At the same time both at finite temperature and out of equilibrium the topological invariance is lost. Moreover, Hall conductivity becomes sensitive to interaction corrections. [ABSTRACT FROM AUTHOR]

In this paper, we present an improved model associated with a three‐dimensional heating model with a stratified DC approach model considering inhomogeneity of ionosphere to study the distributions of characteristic parameters of lower ionosphere during long‐period modulation heating in the polar region. The distributions of Pederson conductivity, Hall conductivity, and excitation current are discussed in detail. The distributions of Pedersen conductivity reveal that the electron temperature plays more important role in spatial distribution of Pedersen conductivity, and the electron density has a small effect on the distribution of Pedersen conductivity. The distributions of Hall conductivity exhibit that the main contribution of the negative disturbance of Hall conductivity comes from the temperature‐dependent electron collision frequency and the positive disturbance comes from electron density. The distributions of excitation current indicate that the amplitude variation of excitation current is dominated by the Pedersen conductivity and Hall conductivity, and the shape variation (the rotation of long axis) of excitation current is dominated by Hall conductivity. Above all, these findings suggest that the difference between steady‐state time scale of electron temperature (milliseconds) and that of electron density (minutes) will greatly administrate the distributions of Pedersen conductivity and Hall conductivity. Excitation current, which leads to the generation of ultralow frequency/extremely‐low frequency/very low frequency, will be further affected. Finally, the estimated amplitude of the magnetic field in model is consistent with the previous experimental results in the long period modulation heating, which proves the accuracy of the model. The amplitude of magnetic field can reach several hundreds of pT at the modulation period of 50 s. Key Points: We present an improved model associated with a three‐dimensional heating model with a stratified DC approach modelThe distributions of Pederson conductivity, Hall conductivity, and excitation current are discussed in detailThe difference between steady‐state time scale of electron temperature and density will administrate the distributions of conductivities [ABSTRACT FROM AUTHOR]

Inertial effects play an important role in classical mechanics but have been largely overlooked in quantum mechanics. Nevertheless, the analogy between inertial forces on mass particles and electromagnetic forces on charged particles is not new. In this paper, we consider a rotating non-interacting planar two-dimensional electron gas with a perpendicular uniform magnetic field and investigate the effects of the rotation in the Hall conductivity. The rotation introduces a shift and a split in the Landau levels. As a consequence of the break of the degeneracy, the counting of the states fully occupied below the Fermi energy increases, tuning the Hall quantization steps. The rotation also changes the quantum Hall plateau widths. Additionally, we find the Hall quantization steps as a function of rotation at a fixed value of the magnetic field.

As the EISCAT UHF radar system in Northern Scandinavia started its operations in the early 1980s, the collected data cover about three solar cycles. These long time-series provide us the opportunity to study long-term variations and trends of ionospheric parameters in the high latitude region. In the present study we have used the EISCAT Tromsø UHF data to investigate variations of the Hall conductivity and ion temperatures in the E-region around noon. Both the ion temperature and the peak altitude of the Hall conductivity are confirmed to depend strongly on solar zenith angle. However, the dependence on solar activity seems to be weak. In order to search for trends in these parameters, the ion temperature and peak altitude of the Hall conductivity data were adjusted for their seasonal and solar cycle dependence. A very weak descent (∼0.2 km/ decade) was seen in the peak altitude of the Hall conductivity. The ion temperature at 110 km shows a cooling trend (∼10 K/ decade). However, other parameters than solar zenith angle and solar activity seem to affect the ion temperature at this altitude, and a better understanding of these parameters is necessary to derive a conclusive trend. In this paper, we discuss what may cause the characteristics of the variations in the electric conductivities and ion temperatures in the high latitude region. [ABSTRACT FROM AUTHOR]

Using a model spectral function of the electron, the Hall conductivity in the normal metallic state of the PrCe xCuO4 (PCCO) superconductor is calculated neglecting the current vertex-correction. The result is qualitatively consistent with the experiment. Consequently, the reason becomes clear why the Fermi-liquid theory fails to explain the anomaly of the Hall conductivity. The inconsistency of the fluctuation-exchange approximation also becomes clear. [ABSTRACT FROM AUTHOR]