Temperature dependence of persistent spin currents in a spin-orbit-coupled electron gas: A density-matrix approach

We present a simple analytical method, based on the canonical density matrix, for the calculation of the equilibrium spin current as a function of temperature in a two-dimensional electron gas with both Rashba and Dresselhaus spin-orbit coupling terms. We find that the persistent spin current is extremely robust against thermal disorder: its variation with temperature is exponentially small (proportional to e(F)(-T)/T) at temperatures much smaller than the Fermi temperature T-F and changes to a power law T-F/T for T > T-F.