Room temperature ferromagnetism (RTFM) was observed in Li-N codoped ZnO thin films [ZnO:(Li,N)] fabricated by plasma-assisted molecular beam epitaxy, and p-type ZnO:(Li,N) shows the strongest RTFM. Positron annihilation spectroscopy and low temperature photoluminescence measurements indicate that the RTFM in ZnO:(Li,N) was attributed to the defect complex related to VZn, such as VZn and Lii-NO-VZn complex, well supported by first-principles calculations. The incorporation of NO can stabilize and enhance the RTFM of ZnO:(Li,N) by combining with Lii to form Lii-NO complex, which restrains the compensation of Lii for VZn and makes the ZnO:(Li,N) conduct in p-type.

Evidence of Cation Vacancy Induced Room Temperature Ferromagnetism in Li-N Codoped ZnO Thin Films. B.Y.Zhang, B.Yao, Y.F.Li, A.M.Liu, Z. Z.Zhang, B.H.Li, G.Z.Xing, T.Wu, X.B.Qin, D.X.Zhao, C.X.Shan, D.Z.Shen: Applied Physics Letters, 2011, 99[18], 182503