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We study dc-current effects on the magnetoresistance oscillation in a two-dimensional electron gas with Rashba spin-orbit coupling, using the balance-equation approach to nonlinear magnetotransport. In the weak current limit the magnetoresistance exhibits periodical Shubnikov-de Haas oscillation with changing Rashba coupling strength for a fixed magnetic field. At finite dc bias, the period of the oscillation halves when the interbranch contribution to resistivity dominates. With further increasing current density, the oscillatory resistivity exhibits phase inversion, i.e., magnetoresistivity minima (maxima) invert to maxima (minima) at certain values of the dc bias, which is due to the current-induced magnetoresistance oscillation.

We examine the shot noise spectrum properties of coherent resonant tunneling in coupled quantum dots (CQDs) in both series and parallel arrangements by means of quantum rate equations and MacDonald’s formula. Our results show that for a series-CQD with a relatively high dot-dot hopping Ω and Ω/Γ>=1 (Γ denotes the dot-lead tunnel-coupling strength), the noise spectrum exhibits a dip at the Rabi frequency 2Ω in the case of noninteracting electrons, but the dip is supplanted by a peak in the case of strong Coulomb repulsion; furthermore, it becomes a dip again for a completely symmetric parallel-CQD by tuning the enclosed magnetic flux. [ABSTRACT FROM AUTHOR]

Presents the results of a study regarding the quantum transport through double-dot Aharonov-Bohm interferometry in Coulomb blockade regime. Results of employing the modified quantum rate equations and the slave-boson approach in the study; Description of the quantum dot; Discussion of the Coulomb correlation effect at arbitrary temperature.

: We study the localization properties of electrons in a two-dimensional model with on-site energies exhibiting long-range correlated disorder. The localization length and conductance of the system are calculated by using the finite size scaling method combined with transfer matrix technique. In the presence of long-range correlations, we find that there is a continuous line of fixed points indicating that the system undergoes a disorder driven Kosterlitz-Thouless-type metal-insulator transition. [ABSTRACT FROM AUTHOR]

Magnetoresistance oscillations in two-dimensional electron systems driven simultaneously by a strong direct current and a microwave irradiation are analyzed within a unified microscopic scheme treating both excitations on an equal footing. The microwave-induced resistance oscillations are described by a parameter εω proportional to the radiation frequency, while the dc-induced resistance oscillations are governed by a parameter εj proportional to the current density. In the presence of both a microwave radiation and a strong dc, the combined parameter εω+εj is shown to control the main resistance oscillations, in agreement with the recent measurement [Zhang et al., Phys. Rev. Lett. 98, 106804 (2007)]. [ABSTRACT FROM AUTHOR]

Recently discovered new structures and zero-resistance states outside the well-known oscillations are demonstrated to arise from multiphoton assisted processes, by a detailed analysis of microwave photoresistance in two-dimensional electron systems under enhanced radiation. The concomitant resistance dropping and the peak narrowing observed in the experiments are also reproduced. We show that the radiation-induced suppression of average resistance comes from virtual photon effect and exists throughout the whole magnetic field range. [ABSTRACT FROM AUTHOR]

It is shown that a finite spin-Hall current can be induced by applying an in-plane magnetic field in a diffusive two-dimensional electron system with the Rashba and Dresselhaus spin-orbit couplings subjected to a dc electric field. The spin-Hall conductivity depends not only on the strength and direction of the magnetic field, but also strongly depends on the form of the scattering potential. It can be negative or positive in the case of remote impurity scattering, but essentially positive in the case of short-range scattering. [ABSTRACT FROM AUTHOR]

Recently discovered modulations of Shubnikov–de Haas oscillations in microwave-irradiated two-dimensional electron systems are shown to arise from electron heating induced by the radiation. The electron temperature, obtained by balancing the energy absorption from the microwave field and the energy dissipation to the lattice through realistic electron-phonon couplings, exhibits resonance. The modulation of the Shubnikov–de Haas oscillation and the suppression of magnetoresistance are demonstrated together with microwave-induced resistance oscillation, in agreement with experimental findings. [ABSTRACT FROM AUTHOR]

Far infrared photoresponse of magnetoresistivity ΔR[sub xx] of two-dimensional electron systems is investigated theoretically at high temperatures. Photon-assisted impurity and phonon scatterings, rather than the electron heating, are shown to be the dominant mechanisms for high-temperature photoresponse at cyclotron resonance. Based on the theory developed for electron magnetotransport driven by intense terahertz radiations, we have calculated the far infrared photoresistivity of a GaAs/AlGaAs heterostructure at temperature T=150 K, predicting notable cyclotron resonance of ΔR[sub xx], in agreement with the experimental finding. Contrary to low temperature case, where the electron heating is almost solely responsible for the cyclotron resonance of ΔR[sub xx], at T=150 K electron-heating contribute at most a small fraction of the total response. © 2003 American Institute of Physics. [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]