Zn 0.99 Cu 0.01 O films were studied experimentally and theoretically. The films were prepared by pulsed-laser deposition on Pt(111)/Ti/SiO 2 /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 exhibit room-temperature ferromagnetism. The sample deposited at 600 • C and an oxygen pressure of 10 Pa showed a large saturation magnetization of 0.83 µ B /Cu. The enhanced ferromagnetism in the (Cu, Li)-codoped ZnO is attributable to the existence of Zn vacancies (V Zn ), as shown by first-principles calculations. The photoluminescence analysis demonstrated the existence of V Zn in both Zn 0.99 Cu 0.01 O and (Cu, Li)-codoped ZnO thin films, and this plays an important role in the increase of ferromagnetism, according to the results of first-principles calculations.

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We report our study on the magnetic properties of Si-doped ZnO thin films fabricated by pulsed laser deposition technique. The Si-doped ZnO thin films show ferromagnetism at room temperature. The saturation magnetism increases from 0 to 2.4 emu/cc with the increasing of Si concentration up to 2%, and then decreases with further increasing of Si concentration. First-principles calculation demonstrates that the origination of ferromagnetism for Si-doped ZnO system is the two unpaired electrons of Si-2p. These unpaired electrons increase the magnetic moments which are responsible for the increasing ferromagnetism.