  Spin-polarized transport of photo-electrons in bulk, p-type GaAs is
investigated in the Pauli blockade regime. In contrast to usual spin diffusion
processes in which the spin polarization decreases with distance traveled due
to spin relaxation, images of the polarized photo-luminescence reveal a
spin-filter effect in which the spin polarization increases during transport
over the first 2 microns from 26 % to 38 %. This is shown to be a direct
consequence of the Pauli Principle and the associated quantum degeneracy
pressure which results in a spin-dependent increase in the minority carrier
diffusion constants and mobilities. The central role played by the quantum
degeneracy pressure is confirmed via the observation of a spin-dependent
increase in the photo-electron volume and a spin-charge coupling description of
this is presented.
