Effect of electrical conduction properties on magnetic behaviors of Cu-doped ZnO thin films

The influence of electrical conduction properties of Cu-doped ZnO (ZnO:Cu) thin films on their magnetic behaviors was investigated. The electrical properties were controlled from n-type to p-type by changing Cu concentration (nCu), which was analyzed by Hall-effect measurements and X-ray photoelectron spectroscopy. The p-type samples with nCu≥1 mol% were obviously ferromagnetic, whilst the n-type samples with nCu≤0.75 mol% exhibited paramagnetism. By increasing nCu from 1 to 3 mol%, the ferromagnetic properties were observed to be degraded due to the existence of Cu and CuO2 anti-ferromagnetic clusters. These results suggest that hole carriers help to couple the ferromagnetic channels in ZnO:Cu.