Oscillations of giant magnetoresistance in Cu/AgCo granular multilayers

Abstract

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.

Magnetoresistance in amorphous oxide films CoFeHfO

“…At low T , the loops are hysteretic and H s reduces slightly. The observed results indicate a granular-like microstructure similar to AgCo films studied earlier [17,18] and suggest that the films with large x consist of magnetic nanoparticles, i.e. Co-Co(Fe) clusters separated by the Hf-O phase which is nonmagnetic and electrically insulating as shown below.…”

Interlayer coupling and magnetoresistance in Ir/Co multilayers

“…Antiferromagnetic (AF) exchange coupling [1] and giant magnetoresistance (GMR) effect [2] were first discovered in multilayered Cr/Fe structures with the transition metal layer used as a spacer. Since then numerous investigations have been reported successively on a variety of magnetic multilayer [3]- [8], granular [9], [10] and layered granular [11] systems. Among them, however, mostly noble metals were used for the spacer or matrix substances, giving large room temperature GMR values, for example exceeding 65% in the Cu/Co system [5], [6].…”