Ferromagnetic mechanism in Ni-doped anatase TiO2

Abstract

The ferromagnetism in Ni-doped anatase TiO2 is studied by a series of supercell density functional calculations. Our results show that O vacancy (VO) plays a key role of ferromagnetism in Ni-doped TiO2, and the magnetic origin is of Ni3+ ion. In the stoichiometric configuration of 2 Ni with one VO, the system shows the ferromagnetic insulating ground state. A vacancy-mediated direct-exchange mechanism is proposed and it reasonably interprets the ferromagnetism in such structure without using the concept of charge carriers.