[show abstract][hide abstract] ABSTRACT: Electric response of spin polarization in two-dimensional electron gas with structural inversion asymmetry subjected to a magnetic field was studied by means of the linear and non-linear theory and numerical simulation with the disorder effect. It was found by Kubo linear reponse theory that an electric resonant response of spin polarization occurs when the Fermi surface is located near the crossing of two Landau levels, which is induced from the competition between the spin-orbit coupling and Zeeman splitting. The scaling behavior was investigated with a simplified two-level model by non-linear method, and the resonant peak value is reciprocally proportional to the electric field at low temperatures and to temperature for finite electric fields. Finally numerical simulation illustrated that impurity potential opens an enegy gap near the resonant point and suppresses the effect gradually with the increasing strength of disorder. This resonant effect may provide an efficient way to control spin polarization by an external electric field.
[show abstract][hide abstract] ABSTRACT: We study the edge spin current and spin polarization in a two-dimensional electron gas with spin-orbit coupling in the presence of a perpendicular magnetic field. The edge effect removes the degeneracy of Landau levels due to the competition between the Rashba coupling and the Zeeman splitting, which exists in the bulk. Large spin edge current and non-linear response to an electric field are found when the two levels are degenerated in the bulk. It is found that he spin current is proportional to spin polarization along the y-direction in an finite magnetic field, which provides a way to extract the spin current in the system.
[show abstract][hide abstract] ABSTRACT: Following a previous work [Shen, Ma, Xie and Zhang, Phys. Rev. Lett. 92, 256603 (2004)] on the resonant spin Hall effect, we present detailed calculations of the spin Hall conductance in two-dimensional quantum wells in a strong perpendicular magnetic field. The Rashba coupling, generated by spin-orbit interaction in wells lacking bulk inversion symmetry, introduces a degeneracy of Zeeman-split Landau levels at certain magnetic fields. This degeneracy, if occuring at the Fermi energy, will induce a resonance in the spin Hall conductance below a characteristic temperature of order of the Zeeman energy. At very low temperatures, the spin Hall current is highly non-ohmic. The Dresselhaus coupling due to the lack of structure inversion symmetry partially or completely suppresses the spin Hall resonance. The condition for the resonant spin Hall conductance in the presence of both Rashba and Dresselhaus couplings is derived using a perturbation method. In the presence of disorder, we argue that the resonant spin Hall conductance occurs when the two Zeeman split extended states near the Fermi level becomes degenerate due to the Rashba coupling and that the the quantized charge Hall conductance changes by 2e^2/h instead of e^2/h as the magnetic field changes through the resonant field.