Ab initio calculations of spin polarization at Co₂CrAl/GaAs interfaces

We investigate the structural and electronic properties of Co ₂CrAl/GaAs (100) and (110) interfaces using density functional theory within the generalized gradient approximation. Adhesion energy is calculated for various interfacial structures, and it is found that the (100) CrAl-terminated surface, which was theoretically predicted to be highly spin polarized, shows weaker adhesion to GaAs than the (100) Co-terminated surface. We then examine the spatial behaviour of local spin polarization at the Fermi level for the (100) and (110) interfaces, choosing the interfacial structures which give rise to relatively large adhesion energy. The (110) interface turns out to have very high spin polarization at the interface, while such behaviour is not observed in the (100) interface.