Effect of interfacial scattering on the magnetoresistance of magnetic tunnel junctions

In theories of electron tunneling between metallic layers, one fundamental question remains: which is the relevant density of states which determines the tunnel current through the barrier? In this letter, the influence of el ectron scattering at the metal/oxide interface in magnetic tunnel junctions on the tunnel current is addressed from a theoretical point of view. Two c ontributions to the tunnel current and to the magnetoresistance of these ju nctions are obtained: one from specular transmission through the barrier wh ich is related to the one-dimensional density of states next to the metal/o xide interface, the other hom tunneling assisted by interfacial scattering which depends bath on the one-dimensional and three-dimensional density of states. The effect of spin-flip scattering on the impurities is discussed a s well.