Effects of Y doping with point defects on the ferromagnetic properties of ZnO(0001)-Zn polar surface

Abstract The ferromagnetic properties of Y-doped ZnO(0001)-Zn polar surface with and without point defects, including oxygen vacancy (VO), hydrogen interstitial (Hi), and zinc vacancy (VZn), are calculated using the first-principles method. Results show that Y-doped ZnO with or without VO is nonmagnetic. Hi in Y-doped ZnO with VO can combine adjacent O atoms to form a bound magnetic polaron. Adjacent H–O bound magnetic polaron (BMPs) create an interconnected BMP cluster, which induces the ferromagnetism of ZnO. Unpaired O-2p electrons induced by VZn causes ZnO to have a long-range ferromagnetic order through the double-exchange mechanism. Ferromagnetic quenching occurs in the ZnO lattice when the ratio of Y to VZn is 2:1. Both ferromagnetic mechanism can be achieved at room temperature.