Vanishing Spin-Hall Conductivity in 2D disordered Rashba electron gas
  For the two-dimensional ideal electron gas with the Rashba spin-orbit interaction and in the presence of non-magnetic short-ranged potential impurities the spin-Hall conductivity $\sigma_{sH}$ is found by direct microscopic calculation. Within the semiclassical approximation $\hbar/\tau \ll \epsilon_F$ and $\Delta \ll \epsilon_F$ the value of $\sigma_{sH}$ is zero for arbitrary ratio of the spin-orbit splitting $\Delta$ and the inverse elastic scattering time $1/\tau$. 
Ol'ga V. Dimitrova