Itinerant-electron theory of ultra-thin Co-Cr superlattices

Abstract

Finite-temperature magnetic properties of Co-Cr superlattices have been studied for the first time within the framework of itinerant-electron theory using the tight-binding model and single-site spin fluctuation theory. The distributions of local magnetic moments on Co and Cr layers are calculated as a function of the temperature in four-layer (1 Co + 3 Cr) bcc superlattices. The interfaces have the [001] orientation. We find that Co magnetic moments couple ferromagnetically across the Co/Cr interface while Cr magnetic moments are stabilized in the commensurate antiferromagnetic state. The temperature dependence of the Co moment (and total magnetization) deviates significantly from the Brillouin function. We suggest that this arises from a weak magnetic interaction across the Co/Cr interface. The theoretical implications for other ferromagnetic/antiferromagnetic interfaces are also discussed. © 1988.