Tunneling Anisotropic Magnetoresistance Driven by Resonant Surface States: First-Principles Calculations on an Fe(001) Surface

Fully relativistic first-principles calculations of the Fe(001) surface demonstrate that resonant surface (interface) states may produce sizable tunneling anisotropic magnetoresistance in magnetic tunnel junctions with a single magnetic electrode. The effect is driven by the spin-orbit coupling. It shifts the resonant surface band via the Rashba effect when the magnetization direction changes. We find that spin-flip scattering at the interface is controlled not only by the strength of the spin-orbit coupling, but depends strongly on the intrinsic width of the resonant surface states.