  We consider spin-dependent tunneling through a gallium arsenide barrier, a
material which has no inversion symmetry. We are dealing with free electrons,
with one effective mass and a spin-splitting in the barrier material. When we
take into account both the spin-orbit interaction and the absence of the
inversion symmetry, the evanescent states in the barrier are spin split and the
tunneling process can become rather involved. Along some crystallographic
directions, the incident wave experiences spin filtering during the tunneling.
These results open stimulating perspectives for spin manipulation in tunnel
devices.
