Role of interfacial mixing in giant magnetoresistance

We show that the giant magnetoresistance in sputtered Ni-Fe/Cu/Ni-Fe/Fe-Mn spin-valve structures is strongly reduced by the presence of compositionally intermixed regions at the NiFe/Cu interfaces. The ultrathin intermixed layers, which are not ferromagnetic, are centers of strong spin-independent scattering, thus reducing the flow of polarized electrons from one ferromagnetic layer to the other. Our results show that interfacial spin-independent scattering must be included in the theory of giant magnetoresistance. © 1993 The American Physical Society.