Spin-polarized ballistic transport in a thin superlattice of zincblende half metallic compounds

We examine theoretically ballistic conduction in a sample made of thin layers of zincblende half metals. The sample is a superlattice consisting of monolayers of GaAs and MnAs, a bilayer of CrAs, and a bilayer of GaAs. The approach is based on density functional theory with the generalized gradient approximation. The superlattice is found to have a half metallic character, and ballistic conduction of electrons within $\sim 0.3$~eV of the Fermi level will give nearly 100\% spin-polarized conductance in the direction of the superlattice. Our calculated results suggest that a thin superlattice involving the MnAs and CrAs will be a good spintronic material and can be grown on GaAs substrate by molecular beam epitaxy.