Transport in Magnetic Layered Structures: Giant Magnetoresistance

Basic features of electronic transport in magnetic layered structures consisting of alternating ferromagnetic and nonmagnetic metallic films are analysed theoretically. The considerations are restricted to magnetoresistance originating from the rotation of the film magnetizations from antiparallel to parallel alignment. The influence of spin-dependent potentials on the transport properties is analysed for both current-in-plane and current-perpendicular-to-plane geometries. Quasi-classical and quantum methods are used to calculate the appropriate conductivity. For current-perpendicular-to-plane geometry the periodic spin-dependent effective electron potential plays an important role and can generate giant magnetoresistance also when the electron scattering by impurities and interface roughness is independent of the spin direction, contrary to the case of current-in-plane geometry when a spin-dependent scattering probability is a necessary condition for the giant magnetoresistance to occur.