Room-temperature ferromagnetism in Er-doped ZnO thin films

Zn1−xErxO thin films have been fabricated on glass substrates by radiofrequency reactive magnetron sputtering. All the films were ferromagnetic at room temperature except for x = 0 and the estimated magnetic moment per Er ion decreased with increasing Er concentration. The presence of any secondary phase was ruled out based on X-ray diffraction and X-ray photoelectron spectroscopy. The ferromagnetism was attributed to the substitution of Er ions for Zn2+ in ZnO lattices, and could be interpreted by the bound-magnetic-polaron model.