Robust room temperature ferromagnetism in Cu doped ZnO thin films

We report the growth of high quality Cu doped ZnO thin films by magnetron sputtering. High level of Cu doping has been achieved at higher growth temperature. Room temperature ferromagnetism, with magnetic moment initially increasing and then decreasing with Cu content, has been observed in the thin film without post growth annealing. Observed ferromagnetism is robust and does not disappear upon annealing.