Enhanced magnetism of Cu(n) clusters capped with N and endohedrally doped with Cr.

The focus of our work is on the production of highly magnetic materials out of Cu clusters. We have studied the relative effects of N-capping as well as N mono-doping on the structural stability and electronic properties of the small Cu clusters using first principles density functional theory based electronic structure calculations. We find that the N-capped clusters are more promising in producing giant magnetic moments, such as 14 μB for the Cu6N6 cluster and 29 μB for the icosahedral Cu13N12 cluster. This is accompanied by a substantial enhancement in their stability. We suggest that these giant magnetic moments of the capped Cun clusters have relevance to the observed room temperature ferromagnetism of Cu doped GaN. For cage-like hollow Cu-clusters, an endohedral Cr-doping together with the N-capping appears as the most promising means to produce stable giant magnetic moments in the copper clusters.