Oscillations of giant magnetoresistance in Cu/AgCo granular multilayers

A novel granular multilayer structure consisting of magnetic granular AgCo layers and non-magnetic Cu spacer layers is introduced to study their magnetotransport properties. The results are similar to those obtained from both conventional multilayers and granular single-films, but with a notable enhancement of low-field sensitivity compared to these structures. This can be attributed to a weak antiferromagnetic coupling across the Cu spacer layer between interfacial Co particles. Direct evidence for this interlayer coupling is given by the observation of magnetoresistance oscillations with variation of the Cu spacer thickness. The oscillation period obtained here for Cu(111) spacer layers is close to 3 atomic layers.