Magnetic Anisotropy of a Single Cobalt Nanoparticle
  Using a new microSQUID set-up, we investigate magnetic anisotropy in a single 1000-atoms cobalt cluster. This system opens new fields in the characterization and the understanding of the origin of magnetic anisotropy in such nanoparticles. For this purpose, we report three-dimensional switching field measurements performed on a 3 nm cobalt cluster embedded in a niobium matrix. We are able to separate the different magnetic anisotropy contributions and evidence the dominating role of the cluster surface. 
M. Jamet, W. Wernsdorfer, C. Thirion, D. Mailly, V. Dupuis, P.   Melinon, A. Perez