Current induced spin flip scattering at interfaces in noncollinear   magnetic multilayers
  We show that when one drives a charge current across noncollinear magnetic layers the two electron Coulomb scattering creates a spin flip potential at interfaces. This scattering is found when the interface potential is updated due to the spin accumulation attendant to charge flow, and it contributes in linear response to the current. With this scattering there is an injection of transverse spin distributions in a layer that propagate, and that in the steady state lead to spin currents transverse to the magnetization. 
Peter M Levy, Jianwei Zhang