Local Mn structure and room temperature ferromagnetism in Mn-doped In2O3 films

Local Mn structure, magnetic, and transport properties in Mn-doped In2O3 films were investigated systematically. The detailed structural analysis and multiple-scattering calculations reveal that Mn2+ ions substitute for In3+ sites of the In2O3 lattice and form MnIn2+ + VO complex with the O vacancy in the nearest coordination shell. All films show clear room temperature ferromagnetism and Mott variable range hopping transport behavior. The saturation magnetization of films increases first, and then decreases with Mn doping, while carrier concentration nc decreases monotonically, implying that the ferromagnetism is not mediated by the charge carriers. These results provide strong evidence that oxygen vacancies play an important role in activating the ferromagnetic interactions in Mn-doped In2O3 films.