Anomalous Hall effect in anatase Ti1−xCoxO2−δ above room temperature

Presence of spin polarized electrons was confirmed by observing anomalous Hall effect in a ferromagnetic semiconductor anatase Ti1−xCoxO2−δ up to 600K. The anomalous Hall resistivity exhibited apparent ferromagnetic hysteresis loop from 300to600K with insignificant change in the magnitude, indicating that the Curie temperature is higher than 600K. The measurements above 500K induced an annealing effect represented by the decrease in resistivity, whereas kept the anomalous Hall resistivity nearly constant.