Coexistence of ultraviolet photo-response and room-temperature ferromagnetism in polycrystalline ZnO thin films

The coexistence of ultraviolet (UV) photoconductivity (PC) and room-temperature ferromagnetism (RTFM) is observed in polycrystalline ZnO thin films deposited by unbalanced magnetron sputtering under high oxygen pressure. A significant increase in PC (∼ 870% to 40 000%) is observed with increasing film thickness and the consequent structural disorder and film porosity. In contrast, the saturation magnetization (MS) at room temperature is found to decrease from 1.02 emu/g to 0.53 emu/g with increasing film thickness from 50 to 150 nm.