Electronic and magnetic properties of V-doped anatase TiO2 from first principles

We report a first-principles study on the geometric, electronic, and magnetic properties of V-doped anatase TiO2. The DFT+U (Hubbard coefficient) approach predicts semiconductor band structures for Ti1-xVxO2 (x=6.25% and 12.5%), in good agreement with the poor conductivity of samples, while the standard calculation within generalized gradient approximation fails. Theoretical results show that V atoms tend to stay close and result in strong ferromagnetism through superexchange interactions. Oxygen vacancy induced magnetic polaron could produce long-range ferromagnetic interaction between largely separated magnetic impurities. The experimentally observed ferromagnetism in V-doped anatase TiO2 at room temperature may originate from a combination of short-range superexchange coupling and long-range bound magnetic polaron percolation.