Effect of the Transition Sublayers at the Interfaces on Giant Magnetoresistance

A thin transition sublayer between the ferromagnetic and the nonmagnetic sublayers is introduced for describing the interface roughness and/or the interface alloying. Based on the Kubo formalism in the real spaces, the giant magnetoresistance effects for both the cases of the structures with and without the transition sublayers at the interfaces are discussed. The numerical results show that the transition sublayers induce a phase shift on the curves of magnetoresistance (MR) vs the thicknesses of the ferromagnetic and the nonmagnetic sublayers, and there exists a critical thickness d_c of the ferromagnetic sublayer, the ratio of the MR values for the structures with and without the transition sublayers at the interfaces changes at the critical thickness.