Spin-Dependent Surface Screening in Ferromagnets and Magnetic Tunnel Junctions

Abstract

We have examined electron screening at the surface of a ferromagnetic metal. In an applied electric field, the surface develops an induced charge and magnetization. This can be described in terms of a novel spin-dependent screening electric field. A set of integrodifferential equations for screening potentials is derived and solved in some limiting cases. The significant implication relevant to spin-polarized transport in field emission and in magnetic tunnel junctions is discussed.