Polycrystalline CrxZn1−xO films and powders were prepared by co-sputtering and sol-gel method, respectively. While room-temperature ferromagnetism was found in as-deposited films, the powders exhibited paramagnetism. Comparison of the structural and magnetic properties of the as-deposited, annealed, and powdered samples indicated that the interstitial Zn, together with Cr doping, plays an important role in the ferromagnetic origin of Cr:ZnO. The ferromagnetism in films could be described by bound magnetic polaron models with respect to defect-bound carriers.

Role of Point Defects in Room-Temperature Ferromagnetism of Cr-Doped ZnO. H.Liu, X.Zhang, L.Li, Y.X.Wang, K.H.Gao, Z.Q.Li, R.K.Zheng, S.P.Ringer, B.Zhang, X.X.Zhang: Applied Physics Letters, 2007, 91[7], 072511