First-principles LDA + U calculations were performed to study the effects of

oxygen vacancies (Vo) on the electronic structure and magnetism in undoped rutile

TiO2-x. Instead of treated as an adjustable parameter, the value of U was determined

by constrained-density-functional calculations. The calculated electronic structure

revealed that the valence electrons released by Vo would occupy mainly the

neighbouring Ti:3d orbital which then becomes spin-polarized due to intra-atomic exchange interaction, thereby giving rise to the half-metallic ferromagnetism. The

magnetization induced by Vo in rutile TiO2-x was almost proportional to the Vo

concentration (x) for x > 0.0625, and becomes 0 for x-values of up to 0.0417.

Oxygen Vacancy Induced Ferromagnetism in Rutile TiO2-x. G.B.Han, S.J.Hu,

S.S.Yan, L.M.Mei: Physica Status Solidi - Rapid Research Letters, 2009, 3[5],

148-50