  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.
