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 nonvanishing spin Hall effect may be recovered for dominantly forward defect scattering.