TiO2: On the possibility of ferromagnetism

Abstract

To see if ferromagnetism can occur in C-doped anatase TiO2, we performed first-principles calculations for a number of C-doped structures in which C atoms substitute O atoms. Our study shows that each C has spin-polarized 2p states in the band gap generating a magnetic moment of 2.0μB. The magnetic coupling between doped C atoms is substantial leading to either antiferromagnetism or ferromagnetism when the C⋯C distance lies between 3–4 Å. A strong ferromagnetic coupling occurs when the two C atoms form a slightly bent C–Ti–C unit by replacing two oxygen atoms at the opposite vertices of a TiO6 octahedron.