Magnetism enhanced layer-like structure of small cobalt clusters

The atomic and electronic structures of CoN clusters (13≤N≤23) are studied by density-functional calculations with generalized gradient approximation. Surprisingly, it is found that CoN clusters appear in layer-like (rather than icosahedral) structures with hcp or fcc stacking, which can be considered as a small fragment of bulk structure. Two structural transitions are identified, in coincidence with photoelectron spectroscopy measurement. The stability of layer-like structures is proved to be enhanced by magnetization.