Zn0.99Cu0.01O films were studied experimentally and theoretically. The films were prepared by pulsed-laser deposition on Pt(111)/Ti/SiO2/Si substrates under various oxygen pressures to investigate the growth-dependence of the ferromagnetic properties. The structural, magnetic, and optical properties were studied, and it was found that all the samples possess a typical wurtzite structure, and that the films exhibited room-temperature ferromagnetism. The sample deposited at 600C and an oxygen pressure of 10Pa showed a large saturation magnetization of 0.83μB/Cu. The enhanced ferromagnetism in the (Cu, Li)-codoped ZnO was attributable to the existence of Zn vacancies (VZn), as shown by first-principles calculations. The photoluminescence analysis demonstrated the existence of VZn in both Zn0.99Cu0.01O and (Cu, Li)-codoped ZnO thin films, and this played an important role in the increase of ferromagnetism, according to the results of first-principles calculations.

The Effects of Zn Vacancies on Ferromagnetism in Cu-Doped ZnO Films Controlled by Oxygen Pressure and Li Doping. Ran, C.J., Yang, H.L., Wang, Y.K., Hassan, F.M., Zhou, L.G., Xu, X.G., Jiang, Y.: Chinese Physics B, 2013, 22[6], 067503