Effects of surface polarity on the structure and magnetic properties of Co implanted polar ZnO wafers

Abstract

Microstructural and magnetic properties of ion implantation method prepared Co doped Zn polar and O polar ZnO wafers are investigated by a combined experimental and theoretical approach. Substantial intrinsic ferromagnetism is observed in all the doped ZnO wafers. The ferromagnetism of Co implanted oxygen polar ZnO wafer is found to be larger than that of zinc polar ZnO. First principle calculations reveal that the magnetic moments mainly come from the Co-3d and O-2p states. The O-2p state has a stronger hybridization with the Co-3d state in oxygen polar ZnO, resulting in higher magnetic moments of Co implanted oxygen polar ZnO. These results not only benefit to a better understanding of the origin of surface-polarity dependent ferromagnetism in ZnO diluted magnetic semiconductors but also may open up the possibility to employ these polar ZnO in spintronic devices.