Density-functional study of structural and electronic properties in O-doped scandium clusters: observation of enhanced magnetic moments

The geometries, stability, electronic properties and magnetism of ScnO clusters up to n = 12 are systematically studied using density-functional theory. For the lowest energy structures of ScnO clusters, the equilibrium site of the O atom is located in the centre of the cluster and surrounded by the Sc atoms except for n = 2, 3 and 5. The calculated results show that clusters with n = 2, 6, 9 and 12 are more stable than their respective neighbours. In addition, the ionization potential (IP), the electron affinity (EA) and the HOMO-LUMO gaps are calculated and discussed. The total magnetic moments of ScnO clusters are larger than YnO except for n = 3 and 5, and also larger than the pure Scn at n = 4 and 7-12, indicating that the O atom can dramatically modify the magnetic properties of Scn, consistent with the observation of enhanced magnetic moments in the ScnO clusters. The lowest energy structure of the Sc12O cluster is a perfect icosahedron with the largest magnetic moment, 10 μB, in the investigated clusters. In addition, we find that the total magnetic moment is not quenched in small ScnO (n = 2-12) clusters. The possible reasons for the high magnetic moments of the clusters are also discussed.