Tunnelling anisotropic magnetoresistance of Fe/GaAs/Ag(001) junctions from first principles: Effect of hybridized interface resonances

Results of first-principles calculations of the Fe/GaAs/Ag(001) epitaxial tunnel junctions reveal that hybridization of interface resonances formed at both interfaces can enhance the tunnelling anisotropic magnetoresistance (TAMR) of the systems. This mechanism is manifested by a non-monotonic dependence of the TAMR effect on the thickness of the tunnel barrier, with a maximum for intermediate thicknesses. A detailed scan of k-resolved transmissions over the two-dimensional Brillouin zone proves an interplay between a few hybridization-induced hot spots and a contribution to the tunnelling from the vicinity of the Gamma-bar point. This interpretation is supported by calculated properties of a simple tight-binding model of the junction which reproduce qualitatively most of the features of the first-principles theory.