Unified picture of spin-dependent transport in GMR multilayered structures and bulk ferromagnetic alloys

Abstract

We have observed a positive (inverse) CPP-MR in magnetic multilayers of the forms: (a) ((X) under bar Y/Cu/Co/Cu)(n) with (X) under bar Y being the alloys <(Fe)under bar>Cr, <(Fe)under bar>V. <(Ni)under bar>Cr, <(Co)under bar>Cr, and (b) (Z/Cr/NiFe/Cr)(n) with Z = Fe and Co, For (a) the inverted results arise primarily from spin-dependent scattering in the bulk of the alloy, and are linked consistently to: (1) their magnetization: (2) band-structure calculations and (3) resistivity of bulk alloys. For (b) samples, the inverse MRs arise primarily from the scattering at the Fe/Cr and Co/Cr interfaces, Inverse MR for X/Y interfaces and X/Y alloys (eg. Fe/Cr and <(Fe)under bar>Cr) arises from the similarity of the matching problem of X and Y d levels at interfaces and in alloys. For all (X) under bar Y the CIP-MR was negative confirming that CIP-MR is strongly influenced by channeling effect and current inhomogenieties. (C) 1996 Elsevier Science B.V. All rights reserved.