Study of the different magnetoresistance sources in Ag/Co multilayers

We report results on magnetoresistance and magnetic properties of sputtered Ag/Co multilayers and their relation to structural properties. We found two components of the magnetoresistance: isotropic and anisotropic. The first one is found to be related to cobalt particles at the interfaces between magnetic and nonmagnetic layers and also to cobalt particles diluted into the silver layers. The other contribution is related to ferromagnetic multidomain Co layers. The results on magnetoresistance and magnetization at low fields, and conductivity measurements, give clear proof of a transition from granular to continuous structure of the magnetic layer. For example, in a Ag/Co multilayer series with silver thickness of 20 Å, such a transition occurs for a cobalt thickness around 5 Å.