Enhanced magnetism in Fe-doped TiO2 anatase nanorods

Simultaneous high-Curie temperature (TC) ferromagnetism and enhanced temperature-independent paramagnetism (χTIP) is quantified in TiO2 anatase nanorods doped with nominal 0.5 at % Fe synthesized by a hydrothermal route. The nanorod dimensions are 8–35 nm in width and several hundred nanometers in length and possess an Fe concentration of 0.3–1.0 at %; no evidence of pure iron nanoparticles is detected. Magnetometry shows ferromagnetism at low fields that transitions to paramagnetism at higher fields with an enhanced temperature-independent susceptibility >100 times that of pure bulk anatase TiO2. The enhanced magnetism is tentatively attributed to the defect structure of the nanorods.