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A momentum balance equation is developed to investigate the magnetotransport properties in monolayer molybdenum disulphide when a strong perpendicular magnetic field and a weak in-plane electric field are applied simultaneously. At low temperature, in the presence of intravalley impurity scattering, Shubnikov–de Haas oscillation shows up accompanied by a beating pattern arising from large spin splitting and its period may halve due to the high-order oscillating term at large magnetic field for samples with ultrahigh mobility. In the case of intervalley disorders, there exists a magnetic-field range where the magnetoresistivity almost vanishes. For a low-mobility layer, a phase inversion of oscillating peaks is acquired in accordance with recent experiment. At high temperature when Shubnikov–de Haas oscillation is suppressed, the magnetophonon resonances induced by both optical phonons (mainly due to homopolar and Frohlich modes) and acoustic phonons (mainly due to intravalley transverse and longitudinal acoustic modes) emerge for a suspended system with high mobility. For the single layer on a substrate, another resonance due to surface optical phonons may occur, resulting in a complex behavior of the total magnetoresistance. The beating pattern of magnetophonon resonance due to optical phonons can also be observed. However, for a nonsuspended layer with low mobility, the magnetoresistance oscillation almost disappears and the resistivity increases with field monotonically. [ABSTRACT FROM AUTHOR]

A balance-equation scheme is developed to investigate the magnetotransport in a dc current biased graphene. We examine the Shubnikov-de Haas oscillation under a nonzero bias current. With an increase in the current density, the oscillatory differential resistivity exhibits phase inversion, in agreement with recent experimental observation. In the presence of surface optical phonons, a second phase inversion may occur at higher dc bias due to the reduced influence of electron heating and the enhanced direct effect of current on differential magnetoresistivity. We also predict the appearance of current-induced magnetoresistance oscillation in suspended graphene at lower magnetic fields and larger current densities. For the graphene mobility currently available (≈20 m2/V s), the oscillatory behavior may be somewhat altered by magnetophonon resonance arising from intrinsic acoustic phonon under finite bias current conditions. [ABSTRACT FROM AUTHOR]

We examine the effect of changing the linear polarization angle θ of incident microwaves with respect to the dc current on radiation-induced magnetoresistance oscillations in a two-dimensional (2D) system within the balance-equation formulation of the photon-assisted magnetotransport model, considering the radiative decay as the sole damping mechanism. At an extremum the amplitude of oscillatory magnetoresistance Rxx exhibits a sinusoidal, up to a factor of 5, magnitude variation with rotating the polarization angle θ. The maximal amplitude shows up generally at a nonzero θ, which is dependent upon the extremum in question, the 2D electron setup, the radiation frequency, and the magnetic field orientation. These results provide a natural explanation for the experimental observations by Mani et al. [ Phys. Rev. B 84 085308 (2011)] and Ramanayaka et al. [ Phys. Rev. B 85 205315 (2012)]. [ABSTRACT FROM AUTHOR]

We examine the nonlinear magnetoresistance oscillations in a dc-biased high-mobility two-dimensional electron system irradiated by intense microwaves with a current-controlled balance-equation model for multi-photon-assisted magnetotransport. It is shown that the maxima/minima positions, particularly the oscillation period of the differential resistance as a function of the ratio of the microwave frequency ω to the cyclotron frequency ωc, strongly depend on the radiation intensity under a large bias dc current density. Theoretical predictions well reproduce the recent experimental findings by Khodas et al. Phys. Rev. Lett. 104 206801 (2010), and support the multiphoton origin of these unusual magnetoresistance oscillations. [ABSTRACT FROM AUTHOR]

Considering finite-temperature screened electron-impurity scattering, we present a kinetic equation approach to investigate transport properties of two-dimensional massive fermions in silicene. We find that the longitudinal conductivity is always nonvanishing when chemical potential lies within the energy gap. This residual conductivity arises from interband correlation and strongly depends on strength of electron-impurity scattering. We also clarify that the electron-impurity interaction makes substantial contributions to the spin and valley Hall conductivities, which, however, are almost independent of impurity density. The dependencies of longitudinal conductivity as well as of spin and valley Hall conductivities on chemical potential, temperature, and gap energy are analyzed. [ABSTRACT FROM AUTHOR]

We study the full counting statistics (FCS) of electron tunneling through a multiterminal quantum dot in the Kondo regime within the slave-boson mean-field theory. By employing the method of Gogolin and Komnik for calculating the FCS generating function based on the nonequilibrium Green's function [Phys. Rev. B 73, 195301 (2006)]. we obtain the counting field λ-dependent self-consistent equations for the mean values of the slave-boson fields and the explicit expression for the derivative of the adiabatic potential of the system with respect to the counting fields. Performing a perturbative expansion to the first order of λ, we find an extra contribution to the shot noise due to the bias-induced Bose field fluctuation, and then confirm that the nonequilibrium particle number fluctuation plays an important role in the current noise of the Kondo dot: enhancement of the current autocorrelation and a positive current cross-correlation. [ABSTRACT FROM AUTHOR]

We present a theoretical investigation for the full counting statistics of the Andreev tunneling through a quantum dot (QD) embedded between superconducting (SC) and normal leads in the presence of a strong on-site electron-phonon interaction using nonequilibrium Green function method. For this purpose, we generalize the dressed tunneling approximation (DTA) recently developed in dealing with inelastic tunneling in a normal QD system to the Andreev transport issue. This method takes account of vibrational effect in evaluation of electronic tunneling self energy in comparison with other simple approaches and meanwhile allows us to derive an explicit analytical formula for the cumulant generating function at the subgap region. We then analyze the interplay of polaronic and SC proximity effects on the Andreev reflection spectrum, current-voltage characteristics, and current fluctuations of the hybrid system. Our main findings include: (1) no phonon side peaks in the linear Andreev conductance; (2) a negative differential conductance stemming from the suppressed Andreev reflection spectrum; (3) a novel inelastic resonant peak in the differential conductance due to phonon assisted Andreev reflection; (4) enhancement or suppression of shot noise for the symmetric or asymmetric tunnel-coupling system, respectively. [ABSTRACT FROM AUTHOR]

Considering the interband correlation, we present a generalized multiple-scattering approach of Green's function to investigate the effects of electron-impurity scattering on the density of states in silicene at zero temperature. The reduction of energy gaps in the case of relatively high chemical potential and the transformation of split-off impurity bands into band tails for low chemical potential are found. The dependency of optical conductivity on the impurity concentration is also discussed for frequency within the terahertz regime. [ABSTRACT FROM AUTHOR]

We exploit the pumped spin-current and current noise spectra under equilibrium conditions in a single quantum dot connected to two normal leads as an electrical scheme for detection of the electron spin resonance (ESR) and decoherence. We propose spin-resolved quantum rate equations with correlation functions in Laplace space for the analytical derivation of the zero-frequency auto- and cross-shot noise spectra of charge and spin current. Our results show that in the strong Coulomb blockade regime, ESR-induced spin flip generates a finite spin current and quantum partition noises in the absence of net charge transport. Moreover, spin shot noise is closely related to the magnetic Rabi frequency and decoherence and would be a sensitive tool to measure them.

Microwave-radiation induced giant magnetoresistance oscillations recently discovered in high-mobility two-dimensional electron systems are analyzed theoretically. Multiphoton-assisted impurity scatterings are shown to be the primary origin of the oscillation. Based on a theory which considers the interaction of electrons with electromagnetic fields and the effect of the cyclotron resonance in Faraday geometry, we are able not only to reproduce the correct period, phase, and the negative resistivity of the main oscillation, but also to predict the secondary peaks and additional maxima and minima observed in the experiments. These peak-valley structures are identified to relate, respectively, to single-, double-, and triple-photon processes.