Interface magnetic anisotropy in cobalt clusters embedded in a platinum matrix

Noninteracting cobalt clusters containing almost one thousand atoms are emb edded in a platinum matrix using a codeposition technique. This one allows us to prepare nanostructured films from miscible elements such as Co/Pt. De posited clusters keep a pure cobalt core surrounded with an alloyed CoPt in terface. Magnetic measurements performed on this cluster assembly reveal a very strong interface anisotropy. Moreover, we find that a simple core-shel l model can account for the observed anomalous temperature dependence of th e cluster magnetization. (C) 2001 Elsevier Science B.V. All rights reserved .