Interfacial roughness, correlation length, and giant magnetoresistances in NiFeCo/Cu superlattices.

Abstract

We have shown by simulating the rocking curve data of x-ray diffraction using diffuse scattering theory that crystalline (111)-oriented NiFeCo/Cu superlattices sputtered on similar NiFeCo buffer layers on glass substrates display substantial correlated interfacial roughness as large as 4\char21{}6 \AA{} with moderately large lateral correlation lengths ranging from 180\char21{}300 \AA{}. A detailed study of the structures, electronic transport in the field, and magnetization characteristics of the superlattices demonstrated explicitly that under similar conditions of antiferromagnetic coupling giant magnetoresistance increases with increasing interfacial roughness, consistent with the theoretical expectation that giant magnetoresistance is enhanced by the presence of diffuse interface scattering. The experimental results suggest that interfacial roughness chiefly arises from interface disorder at the interfaces. \textcopyright{} 1996 The American Physical Society.