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Fe/Sn-codoped In2O3 powders and films are prepared by a vacuum annealing process and a pulsed laser deposition technique, respectively. The structural and magnetic properties of the samples are investigated. The obvious room-temperature ferromagnetism is observed in both (In0.92Fe0.05Sn0.03)(2)O-3 powders and films, but their magnetic behaviors are very different. The ferromagnetism of the vacuum-annealed powders is partially due to precipitated Fe3O4 impurity. By contrast, the ferromagnetism of the films is intrinsic and does not originate from any magnetic impurity, as confirmed by the extensive x-ray absorption spectroscopy and magnetization studies.

Mn and Cr-doped In2O3 films with Sn codoping were deposited on sapphire substrate by pulsed laser deposition. The ferromagnetism of Mn-doped In2O3 films shows reversible behavior, which can be switched between “on” and “off” states by controlling the carrier density via varying Sn concentration. The enhanced ferromagnetism in Cr-doped In2O3 films is observed due to the significant increase in the carrier density with Sn doping, and the saturation magnetization can reach 2.10 μB/Cr. Most importantly, both of the experiment results reveal that the carrier density and the net spin are two crucial factors for producing and tuning ferromagnetism.