Magnetic nanostructures of mixed cobalt-samarium clusters

We synthesized Co-Sm mixed clusters from a SmCo5 solid target mounted in a laser vaporization source. We studied both pure nanostructured SmCo5-cluste r-assembled films and the same isolated clusters embedded in a matrix. The supported cluster size distribution centered around 3 nm was determined fro m transmission electron microscopy observations. Mass spectra obtained on t he photoionized clusters in the gas phase and Rutherford backscattering spe ctrometry analyses performed on 100-nm-thick films confirm the conservation of the compound-target stoicheiometry in both free and deposited clusters. However, X-ray photoemission spectroscopy measurements seem to indicate a segregation of samarium at the cluster surface. This segregation effect cou ld explain the low Values of the magnetization and coercive fields obtained from magnetometry measurements with respect to those in the bulk SmCo5 cry stallized phase.