Oxygen vacancy and Mn2+ induced ferromagnetism in Mn-doped ZnO thin films

With the purpose of investigating the origin of ferromagnetism (FM), Mn-doped ZnO thin films had been fabricated by radio frequency (rf) magnetron sputtering and subsequent anneal process. The characterization of the Mn-doped ZnO thin films was conducted by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and superconducting quantum interference device (SQUID). With increasing the anneal temperature from 300°C to 700°C for 3 min, the influence on magnetism of the Mn-doped ZnO thin films is slight. While extending the anneal time from 3 to 50 min at 300°C, the influence on magnetism is obvious and the Mn-doped ZnO thin films with 30 min clearly demonstrate FM. Compared with the effect of oxygen vacancy and substitutional Mn 2+ on the ferromagnetic behavior, O V plays the main role in inducing FM of the Mn-doped ZnO thin films with good crystal structure.