Magnetic properties of cluster-beam-synthesized cobalt: Noble-metal films

A cluster-beam deposition technique has been used to produce magnetic clusters embedded in a nonmagnetic matrix. We report here on films with cobalt clusters of average diameter of 5.5 nm embedded both in Cu and Ag. Volumetric concentrations of Co ranged from 10% to 50%. Magnetization and low temperature hysteresis loops, both field cooled (FC) and zero-field cooled (ZFC), have been measured between 4.2 and 300 K. The FC and ZFC magnetization bifurcate at or above room temperature with the clusters having a nonzero remanence at room temperature. Low temperature hysteresis loops exhibit a two-phase nature with one phase displaying exchange bias upon field cooling, suggesting the presence of an oxide phase. Conditions under which the oxide is present have been studied. (C) 2000 American Institute of Physics. [S0021- 8979(00)47408-6].