We construct the theory of ferromagnetism in magnetically doped oxygen deficient anatase TiO2. The theory is based on the assumption that substitutional transition metal ions form complex defects with oxygen vacancies VO. Complex formation is accompanied by charge transfer from vacancies to magnetic impurities. The mechanism of FM coupling is a superexchange between magnetic ions via empty levels generated by oxygen vacancies. The long range FM order in the system of vacancy-impurity complexes arises when the concentration of VO exceeds the percolation threshold.
- Dilute magnetic dielectrics