Ballistic spin injection from Fe(001) into ZnSe and GaAs

Abstract

We consider the spin injection from Fe into ZnSe and GaAs in the ballistic limit. By means of the ab initio screened Korringa-Kohn-Rostoker method we calculate the ground-state properties of epitaxial $\mathrm{Fe}|\mathrm{ZnSe}(001)$ and $\mathrm{Fe}|\mathrm{GaAs}(001)$ heterostructures. Three injection processes are considered: injection of hot electrons and injection of ``thermal'' electrons with and without an interface barrier. The calculation of the conductance by the Landauer formula shows that these interfaces act like a nearly ideal spin filter, with spin polarization as high as 99%. This can be traced back to the symmetry of the band structure of Fe for normal incidence.