Oxygen-defect-induced magnetism to 880 K in semiconducting anatase TiO2−δ films

We demonstrate a semiconducting material, TiO 2−δ , with ferromagnetism up to 880 K, without the introduction of magnetic ions. The magnetism in these films stems from the controlled introduction of anion defects from both the film–substrate interface as well as processing under an oxygen-deficient atmosphere. The room-temperature carriers are n-type with n ~3 × 10 17  cm −3 . The density of spins is ~10 21  cm −3 . Magnetism scales with conductivity, suggesting that a double exchange interaction is active. This represents a new approach in the design and refinement of magnetic semiconductor materials for spintronics device applications.