Spin depolarization in the transport of holes across   GaMnAs/GaAlAs/p-GaAs
  We study the spin polarization of tunneling holes injected from ferromagnetic GaMnAs into a p-doped semiconductor through a tunneling barrier. We obtain an upper limit to the spin injection rate. We find that spin-orbit interaction interaction in the barrier and in the drain limits severely spin injection. Spin depolarization is stronger when the magnetization is parallel to the current than when is perpendicular to it. 
L. Brey, J. Fernandez-Rossier, C. Tejedor