Electrical detection of spin accumulation in a p-type GaAs quantum well
  We report on experiments in which a spin-polarized current is injected from a $GaMnAs$ ferromagnetic electrode into a $GaAs$ quantum well through an AlAs barrier. The resulting spin polarization in the GaAs well is detected by measuring how the current, tunneling to a second $GaMnAs$ ferromagnetic electrode, depends on the orientation of its magnetization. Our results can be accounted for the non-relaxed spin splitting of the chemical potential, that is spin accumulation, in the $GaAs$ well. We discuss the conditions on the hole spin relaxation time in GaAs that are required to obtain the large effects we observe. 
R. Mattana, J.-M. George, H. Jaffres, F. Nguyen Van Dau, A. Fert, B.   Lepine, A. Guivarc'h, G. Jezequel