Spin textures and magnetotransport properties in cobalt/ruthenium and cobalt/palladium bilayers

Abstract

We report on resistivity, magnetoresistance, and Hall effect experiments in bilayer thin films of cobalt/ruthenium (Co/Ru) and cobalt/palladium (Co/Pd) prepared by magnetron sputtering. The resistivity and magneto-transport properties of single layers of the same materials were also measured. For analyzing the results in the bilayers, we propose an approach based on a two-current model that assumes a current mixing effect coming from the large contact area between films. The method is devised for identifying the effects related to the interface between the metallic films. The outcome of the analysis indicates that significant interface effects occur in both studied bilayers. The role of the Dzyaloshinskii-Moriya interaction and the related spin arrangements formed at the interface are pointed out. Particularly for the Co/Pd system, from the magnetoresistance and Hall resistivity results possible evidence is obtained for the occurrence of non-trivial chiral spin textures in the field range corresponding to the initial process of magnetization.