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-cluster-assembled films and the same isolated clusters embedded in a matrix. The supported cluster size distribution centered around 3 nm was determined from transmission electron microscopy observations. Mass spectra obtained on the photoionized clusters in the gas phase and Rutherford backscattering spectrometry 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 could explain the low values of the magnetization and coercive fields obtained from magnetometry measurements with respect to those in the bulk SmCo₅ crystallized phase. [ABSTRACT FROM AUTHOR]