Suppression of the Persistent Spin Hall Current by Defect Scattering
  We study the linear response spin Hall conductivity of a two-dimensional electron gas (2DEG) in the presence of the Rashba spin orbit interaction in the diffusive transport regime. When defect scattering is modeled by isotropic short-range potential scatterers the spin Hall conductivity vanishes due to the vertex correction. A non-vanishing spin Hall effect may be recovered for dominantly forward defect scattering. 
Jun-ichiro Inoue, Gerrit E.W. Bauer, Laurens W. Molenkamp