Structural and Magnetic Property of Ion Irradiated TiO₂ Single Crystals

Ferromagnetism is induced in pure TiO₂ single crystals by oxygen ion irradiation. The ferro-magnetism is observed up to room temperature and is with weak temperature dependence. By combining X-ray diffraction, Rutherford backscattering/channelling, Raman scattering, and electron-spin resonance spectroscopy, supperconducting quantum interference device, displacement per atom, we measured the lattice damage accumulation with increasing flu-ences. A defect complex, i.e., Ti³⁺ on the substitutional accompanied by oxygen vacancies, has been identified in the irradiated TiO₂. This kind of defect complex results in a local (TiO_6-x) stretching Raman mode. We elucidate that Ti³⁺ with one unpaired 3d electron provide the local magnetic moments.