Charge and spin conductivity of a two-dimensional electron gas with random Rashba interaction

Abstract

We calculate the transport relaxation time ${\tau }_{\mathrm{tr}}$ and spin transport relaxation time ${\tau }_{s,\mathrm{tr}}$ for a two-dimensional electron gas with spatially fluctuating Rashba spin-orbit interaction. These relaxation times determine the electrical and spin conductivity of the two-dimensional system, respectively. It is shown that the transport relaxation time ${\tau }_{\mathrm{tr}}$ is a nonmonotonic function of electron energy $\epsilon$, whereas the spin transport relaxation time ${\tau }_{s,\mathrm{tr}}$ decreases with increasing $\epsilon$, similarly to the conventional electron relaxation time $\tau$ that characterizes the decay of an electron state corresponding to certain values of the momentum and spin. Such a behavior of the relaxation times leads to unusual temperature dependence of the electrical and spin conductivity.

7 pages, 4 figures