Origin of Ferromagnetism in Co-Ion-Implanted Anatase TiO₂ Thin Films

Abstract

Ferromagnetic Co-doped anatase TiO2 films were prepared by implantation of Co ions into TiO2 thin films using a metal vapor vacuum arc ion source at various beam currents. The saturation magnetization (Ms) of these films increased with annealing temperature. The maximum Ms observed was about 2.3 µB/Co. High-resolution transmission electron microscopy and X-ray photoelectron spectrometry were performed to study the possible origin of the ferromagnetism. It is believed that the high magnetic moment values observed are associated with Co atoms doped to the Ti2+ sites and the intermediate spin state.