First-principles study of ferromagnetism in N doped TiO 2 and TiO

N doped TiO is nonmagnetic, in which spin-split impurity states are not induced near the Fermi energy (EF) by N dopant. N doped TiO2 along with transition-metal (TM) doped TiO is magnetic, in which spin-split impurity states are induced across EF. The magnetic moment is determined by the 3d4s electron configurations and the valence states of TM-dopant ions when they substitute Ti. Hence, the origin of ferromagnetism of N doped TiO2 and TiO is not closely related to the width of the band gaps of host oxides, but would be crucially related to that if the dopant can induce spin-split impurity states near EF.