Theory of Magnetoresistance in Multilayers

Recently it has been found that metallic multilayer films exhibit novel phenomena, particularly giant magnetoresistance in Fe/Cr, Co/Cu, Co/Cu/NiFe/Cu, and other multilayers. In this review, we explicate the theory of the giant magnetoresistance effect, placing emphasis on its mechanism and dependence on the constituent materials of multilayers. Some relations between the giant magnetoresistance, the electrical resistivity of the magnetic alloys, and the anisotropic magnetoresistance are also discussed.