X-ray diffraction, X-ray energy dispersive spectrometer, photoluminescence, electron paramagnetic resonance were performed to examine the evolution of intrinsic defect states during the annealing treatment for understanding the origin of ferromagnetism in undoped ZnO granular films deposited by the magnetron sputtering method. A strong link between the ferromagnetism and the zinc vacancies was established, indicating zinc vacancies may be more effective in modulating ferromagnetism than oxygen vacancies in ZnO. This novel observation was significant not only to get further insight into the ferromagnetic origin but also to tune the magnetic properties for spintronic materials.

Role of Zinc Vacancies in Driving Ferromagnetism in Undoped ZnO Granular Films. Xu, X., Xu, C., Chen, G., Wu, J., Hu, J.: EPL, 2013, 101[2], 27009