First-principles study on stability and magnetism of AlnZn (n=1–9) clusters

We have investigated the structures, stabilities and magnetism of zinc-doped Aln (n=1–9) clusters in detail by using first-principles density functional theory. Our calculated results indicate that the ground state structures of the mixed AlnZn (n=1–9) clusters doped with one zinc atom can be obtained from the most stable structures of the pure Aln (n=2–10) clusters by substitutional type. The impurity atom causes local structural distortion due to different atomic radii and different bonding characteristics. It is found that the clusters with total atom numbers of 3 and 7 exhibit high stability. In addition, the energy gaps Egs between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) show obvious even/odd alternation with cluster size. Furthermore, we investigate the magnetism of the mixed clusters. The Al4Zn, Al6Zn and Al8Zn clusters with even number of electrons do not have any magnetism. All Al1Zn, Al5Zn, Al7Zn and Al9Zn clusters have the total magnetic moment of 1.0 μB due to one unpaired electron. Unexpectedly, the Al2Zn and Al3Zn clusters show total magnetic moments of 2.0 and 3.0 μB, respectively. The magnetism arises from the sp–d hybridization due to charge transfer and the influence of the impurity zinc atom.