Magnetic x-ray circular dichroism has been used to measure the room-temperature magnetization of cobalt clusters embedded in a copper matrix. It is found that the magnetization depends on the average cluster size and concentration but, in all cases, is significantly less than that of a thin cobalt film even at magnetic fields of 4 T. Various mechanisms for this behaviour are discussed including the possibility that there are significant cluster - matrix and cluster - cluster exchange interactions. Anomalously large values of the ratio of the average orbital to spin moment, measured for some samples, may be a signature of antiferromagnetic exchange coupling. Antiferromagnetic coupling of clusters would necessitate a stronger interaction than can be predicted with RKKY theory and the possibility that this coupling is a `superexchange' mechanism is discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.