Temperature-dependent magnetoresistance of ZnO thin film

A ZnO film was deposited, and the magnetic and the magnetoresistive (MR) properties were studied. The MR measurements reveal negative MR at 80, 50, 20, 10 and 6 K, which is supposed to be induced by the weak-localization effect, based on a logarithmic dependence of the electrical conductivity on temperature. When temperature was reduced to be 2 K, a positive MR was observed. We suggest that it is related to the spin splitting induced by exchange interaction between itinerant electrons and vacancy defects in ZnO. Through the magnetic measurement, it is found that ZnO shows ferromagnetism. It is suggested that the observed ferromagnetism is correlated with the exchange interaction.