Magnetic studies on mn-doped TiO2 bulk samples

Mn-doped TiO2 (Ti1-xMnxO2) bulk samples with nominal composition x = 0.02, 0.04, 0.08 have been prepared by a solid-state reaction and sintered at different temperatures ranging from 450 degrees C to 900 degrees C. For samples with x = 0.02, magnetic investigations show that room temperature ferromagnetism can be obtained and the magnetization of samples decreases monotonically with the increase in the sintering temperature. For the samples sintered at 600 degrees C with different doping content, the temperature dependence of magnetic susceptibility shows that a magnetic transition appears near room temperature, besides a magnetic transition at 43 K perhaps caused by Mn3O4. From the extrapolation of the inverse magnetic susceptibility curves at high temperatures, a positive Curie-Weiss temperature is obtained and it shifts to a low temperature with Mn doping content, revealing that ferromagnetic coupling decreases monotonically with the increase in Mn doping content. In addition, an exchange bias is clearly observed below 60K, which also provides strong evidence that Ti1-xMnxO2 is ferromagnetic.