Room-temperature ferromagnetism in carbon- and nitrogen-doped rutile TiO₂

Marked room-temperature ferromagnetism (RTFM) was obtained in carbon- and nitrogen-doped rutile (Formula presented.) powders. X-ray photoelectron spectroscopy measurements revealed the co-existence of considerable densities of states near the Fermi level ((Formula presented.)) and oxygen vacancies primarily induced by C- and N-doping. Density functional theory calculations showed that the local moments responsible for the observed RTFM in N-doped (Formula presented.) were primarily attributed to the partially populated, spin-polarized Ti (Formula presented.) band. In addition to the unfilled Ti (Formula presented.) band, the spin splitting in C (Formula presented.)states near (Formula presented.) in C-doped (Formula presented.), which may be induced by the (Formula presented.) interaction between the C impurities and neighboring oxygen ions, results in Stoner band-splitting-type ferromagnetism.