Role of point defects in room-temperature ferromagnetism of Cr-doped ZnO

Polycrystalline CrxZn1−xO films and powders are prepared by cosputtering and sol-gel method, respectively. While room-temperature ferromagnetism is found in as-deposited films, the powders exhibit paramagnetism. Comparison of the structural and magnetic properties of the as-deposited, annealed, and powdered samples indicates that the interstitial zinc, together with Cr doping, plays an important role in the ferromagnetic origin of Cr:ZnO. The ferromagnetism in films can be described by bound magnetic polaron models with respect to defect-bound carriers.

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