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

We calculate the transport relaxation time τ_tr and spin transport relaxation time τ_{s ,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 τ_tr is a nonmonotonic function of electron energy ɛ , whereas the spin transport relaxation time τ_{s ,tr} decreases with increasing ɛ , similarly to the conventional electron relaxation time τ 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.