Interplay between carrier and cationic defect concentration in ferromagnetism of anatase Ti_1-xTa_xO₂ thin films

Thin films of Ta incorporated TiO₂ grown by pulsed laser deposition under specific growth conditions show room temperature ferromagnetism. Ta introduces carriers and concomitantly cationic defects, the combination of which leads to ferromagnetism. In this paper, we report on the dependence of the carrier and cationic defect density (compensation) on various parameters such as oxygen growth pressure, temperature and Ta concentration. Most likely, the Ti vacancies act as magnetic centers and the free electrons help with the exchange leading to ferromagnetism via Ruderman-Kittel-Kasuya- Yosida mechanism.