Influence of Au and Ag at the interface of sputtered giant magnetoresistance Fe/Cr multilayers

Multilayer films consisting of 20-Å Fe and 15-Å Cr with amounts of Au and Ag varying from 0 to 4 Å deposited at alternate Fe/Cr interfaces have been RF-diode-sputtered, and their magnetic and magnetotransport properties have been measured. When no noble metal is included, the films exhibit strong antiparallel coupling between adjacent Fe layers, with saturation fields as large as 7 kOe, and giant magnetoresistance (GMR) of 6% at 300 K, similar to that of MBE (molecular beam epitaxy)-grown films reported by others. The interruption of intimate contact between Fe and Cr at the interface resulting from noble-metal deposition gives rise to a substantial decrease in the magnitude of the GMR and the interfacial coupling. This suggests that the mechanism of GMR is associated with Fe and Cr in contact, as is required by models invoking spin-dependent impurity scattering. The results also suggest that the antiparallel coupling arises from direct exchange