Cr-doped TiO2 anatase: A ferromagnetic insulator

Abstract

Epitaxial ferromagnetic films of Cr-doped TiO2 anatase (CrxTi1−xO2−x∕2) were grown on LaAlO3(001) using oxygen-plasma-assisted molecular-beam epitaxy. CrK-shell x-ray absorption near-edge spectroscopy shows that the formal oxidation state of Cr is +3 throughout the films, with no evidence for either elemental Cr or half-metallic CrO2. Cr is found to substitute for Ti in the lattice, with uniform distribution throughout the doped region of the film. The Cr-doped anatase films exhibit room-temperature ferromagnetism aligned in-plane, with a saturation magnetization of ∼0.6μB/Cr atom.