Structures, stabilities, and magnetic properties of Cu-doped Zn _nO _n (n=3,9,12) clusters: A theoretical study

摘要

The structural, electronic, and magnetic properties of Cu-doped Zn _nO _n (n=3,9,12) clusters have been studied using spin-polarized density functional theory. We firstly investigate the lowest-energy structures of pure Zn _nO _n (n=1-13) clusters based on the extensive searching, and identify that the Zn _3O _3, Zn 9O 9 and Zn _(12)O _(12) clusters possess relatively higher stability. Then, these stable clusters are taken as candidates for investigating the effect of Cu-atom doping. Three doping modes, that is, substitutional, exohedral, and endohedral doping, are considered. It is found that the substitutional mono- and bi-doped clusters are the most stable among doped clusters. The HOMO-LUMO gaps of the doped clusters are all reduced due to the p-d hybridization caused by the Cu-atom doping. For the monodoped clusters, all isomers have a magnetic moment of 1μ B, which is mainly contributed by the Cu _3d and Cu-surrounding O _2p states. However, for the bidoped clusters, the ground states have zero magnetic moment with the spins on the Cu atoms being either antiferromagnetically coupled or completely quenched, except for Cu _2ZnO _3 cluster.