Enhanced magnetism of Cu$_n$ clusters capped with N and endohedrally doped with Cr

TL;DR

This study demonstrates that N-capping and Cr-doping significantly enhance the magnetic properties and stability of Cu clusters, potentially explaining room temperature ferromagnetism in Cu-doped GaN.

Contribution

It introduces a first-principles analysis showing how N-capping and Cr-doping induce giant magnetic moments in Cu clusters, advancing magnetic material design.

Findings

N-capped Cu clusters exhibit giant magnetic moments up to 29 μ_B.

N-capping enhances the stability of Cu clusters.

Endohedral Cr-doping with N-capping produces stable giant magnetic moments.

Abstract

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 $\mu_B$ for the Cu$_6$N$_6$ cluster and 29 $\mu_B$ for the icosahedral Cu$_{13}$N$_{12}$ clusters. This is accompanied by a substantial enhancement in their stability. We suggest that these giant magnetic moments of the capped Cu$_n$ 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.