Magnetism due to oxygen vacancies and/or defects in undoped semiconducting and insulating oxide thin films

Room temperature ferromagnetism was observed in HfO2, TiO2, and In2O3 films grown on yttrium-stabilized zirconia, LaAlO3, and MgO substrates, respectively. While the magnetic moment is rather modest in the case of In2O3 films, it is very large in the other two cases. Thin film form, which might create necessary defects and/or oxygen vacancies, must be the main reason for undoped semiconducting and insulating oxides to become ferromagnetic. From the results, a serious question arises if a transition-metal doping indeed plays any essential role in producing ferromagnetism (FM) in non-magnetic oxides.