Room temperature ferromagnetism in Mn-doped γ- Ga₂O ₃ with spinel structure

Mn-doped Ga2 O3 (7 cation % of Mn) thin film has been grown on c -cut sapphire substrate using pulsed-laser deposition technique. Electron diffraction analyses by transmission electron microscopy found that the Mn-doped film shows γ phase with spinel structure, which is different from undoped film showing Β phase. No secondary phase can be detected. Combination of Mn- L2,3 near edge x-ray absorption experiments with first-principles many-electron calculations unambiguously implies that Mn atoms are located at tetrahedrally coordinated Ga sites with a valence of +2. The doped sample shows ferromagnetism up to 350 K.