First-principles study of structural, electronic and magnetic properties of Co13−nMn (n = 1, 2, M = Mn, V and Al) clusters

The geometries, stabilities, electronic and magnetic properties of Co13−nMn (n = 1, 2, M = Mn, V and Al) clusters have been systematically studied by means of a density functional theory with generalized gradient approximation. The calculated results show that the most stable structures of Co12M and Co11M2 (M = Mn, V and Al) clusters all prefer icosahedral configurations with high symmetry, in which the Mn and Al atoms prefer to occupy surface positions of the icosahedron, while the V atom favors the central position. In these clusters, the Al atoms have nearly zero local magnetic moments, while Mn and V atoms are coupled with the remaining Co atoms ferromagnetically and antiferromagnetically, respectively. These several kinds of different magnetic behaviors result in the total magnetic moment enhancement with doped Mn and reduction with doped V/Al as compared to the optimal icosahedral structure of Co13 cluster, in good agreement with recent Stern-Gerlach experiment results [26,31]. Analysis based on the binding energy and density of state has been made to clarify different magnetic behaviors of the Co12M and Co11M2 (M = Mn, V and Al) clusters. In addition, our calculations suggest that in the Stern-Gerlach molecular beam the Co12M and Co11M2 (M = Mn, V and Al) alloy clusters mainly exist as icosahedral structures.