Room temperature ferromagnetism was observed in undoped TiO2 films deposited on Si substrates using pulsed laser deposition. The ferromagnetic properties of the samples depend on the oxygen partial pressure during the pulsed laser deposition synthesis. The appearance of higher binding energy component in the oxygen 1s core peak from X-ray photo-electron spectroscopy suggested the presence of oxygen vacancies in these samples. The amount of oxygen during the synthesis determines the vacancy concentration in the samples which was directly related to the magnetic behavior of the samples. The magnetic moment decreased with oxygen vacancy concentration in the samples. Valence band measurements were used to study the electronic structure of both stoichiometric and reduced TiO2. The analyses revealed the presence of a Ti 3d band near the Fermi level in reduced TiO2 samples. These bands were otherwise empty in stoichiometric TiO2 and reside in the conduction band which makes them unobservable by X-ray photo-electron spectroscopy. The existence of this Ti 3d band near the Fermi level could possibly lead to Stoner splitting of the band.

Experimental Studies on Vacancy Induced Ferromagnetism in Undoped TiO2. Rumaiz, A.K., Ali, B., Ceylan, A., Boggs, M., Beebe, T., Ismat Shah, S.I.: Solid State Communications, 2007, 144[7-8], 334-8