Characteristic giant magnetoresistance of Fe/Cu granular films produced by cluster beam deposition and subsequent annealing

FexCu100 −x granular films have been synthesized by a cluster beam technique. The magnetoresistance (MR) ratio monotonically increases with decreasing Fe content. This MR behavior is ascribed to the change in the magnetic states of Fe clusters. Mössbauer spectrum at 5 K indicates that the small fcc Fe clusters carry large magnetic moment at around x = 9, whereas the fcc Fe phase reveals antiferromagnetism at around x = 22. After subsequent annealing at 673 K for 30 min, these Fe clusters grow and form larger ferromagnetic bcc Fe clusters and MR shows a maximum at around x = 15.