Room temperature ferromagnetism in swift heavy ion irradiated V doped ZnO thin films

In the present study, we have investigated the effect of 50 MeV Ag-ions irradiation on structural, optical and magnetic properties of pure ZnO, Zn0.95V0.05O and Zn0.90V0.10O thin films. X-ray diffraction (XRD) analysis of the films before and after ion irradiation confirms that all the films are in (002) preferred orientation. Upon ion irradiation, the increase of full width at half maximum (FWHM) and decrease of XRD intensity of (002) diffraction peak are observed. Photoluminescence (PL) spectra of ion irradiated films exhibit strong defect related emission about similar to 2.45 eV. It might be attributed to the defects such as oxygen vacancies in the film. The formation of oxygen vacancies upon ion irradiation resulting increase in band gap of pure ZnO, Zn0.95V0.05O and Zn0.90V0.10O thin films. The ion irradiated Zn0.95V0.05O and Zn0.90V0.10O films exhibit strong room temperature ferromagnetism as evidenced from VSM measurements. It is conclude that the spin associated with V ions together with increasing concentration of oxygen vacancies favours enhanced ferromagnetic behaviour in irradiated V doped ZnO films.