Spin torque induced spin current in a two-dimensional tight-binding system with Rashba coupling in the presence of random impurities

Abstract

The effect of Rashba spin-orbit interaction on quantum transport in a two-dimensional tight-binding system is studied in the presence of random impurities. The relaxation time for the impurity scattering is calculated using the Matsubara Green function technique and the spin and charge conductivities are determined using the Kubo formalism. The relaxation time, charge and spin conductivities are shown to exhibit peak structures at a critical chemical potential, the peak of the spin conductivity being higher than that of charge conductivity. It is also shown that the Rashba interaction increases the peaks of the charge and spin conductivities, while the impurity coupling decreases them. In case of relaxation time, however, the peak value remains unaffected by RSOI. It is furthermore shown that in general, the relaxation time, and charge and spin conductivities are enhanced by RSOI while they are reduced by impurities.