The tunneling anisotropic magnetoresistance (TAMR) in epitaxial tunnel junctions FM/I/NM, where FM denotes a ferromagnetic metallic electrode, NM a non-magnetic metallic electrode, and I an insulating (semiconducting) spacer layer, represents a phenomenon with potential applicability in spintronics. In this contribution, we present results of a first-principles study of this phenomenon for the system Fe/GaAs/Ag(001) and of a model study for the FM/I/NM junctions within a simple tight-binding approach. Our main attention will be focused on the dependence of the in-plane TAMR on the thickness of the tunnel barrier. We show that this dependence can be non-monotonic with a maximum TAMR value for intermediate barrier thicknesses. This feature is explained due to hybridized interface resonances formed at both interfaces of the junction and manifested as hot spots in k-resolved conductances. |