Intrinsic Ferromagnetism Observed in ZnO Thin Film

摘要

A ZnO film was deposited on a silicon wafer by magnetron sputtering, and the magnetic and the electronic properties have been studied. The magnetic property measurements show that the ZnO film is ferromagnetic at room temperature. Through the magnetoresistance (MR) measurement, it is found that ZnO reveals a negative MR at 80, 50, 20, 10 and 6 K, which is induced by the weak-localization effect. However, a positive MR as large as 19.8percent was observed, when temperature was reduced to 2 K. As far as the mechanism of the huge positive MR is concerned, it is suggested to be due to the spin splitting induced by the s-d-like interaction. Through the discussion on the huge positive MR, we demonstrate that the observed ferromagnetism in ZnO is intrinsic, not from external impurities.