LAUSR

Abstract Sn 1-x Fe x O 2 (x = 0, 0.023, 0.042 and 0.075) films were prepared by radio frequency magnetron sputtering. X-ray diffraction shows that Fe doping does not alter the tetragonal rutile structure of SnO 2 . X-ray absorption fine structure (XAFS) characterization shows that no Fe metal clusters or secondary phases are formed and that Fe 2+ and Fe 3+ coexist and substitute the Sn sites with oxygen vacancies to compensate charge nonequilibrium in the Fe-doped SnO 2 films. Fe 2p and asymmetric O 1s XPS spectra further verify the existence of Fe 2+ /Fe 3+ , lattice oxygen (Sn O band) and anionic vacancies. The room temperature ferromagnetism of the films has a strong dependence on Fe-doping level. The saturation magnetization increases with increasing the Fe doping level, whereas the carrier concentration decrease. Which implies that the ferromagnetism is not mediated by carriers. The bound magnetic polarons resulted from the oxygen vacancies play a key role in the observed room temperature ferromagnetism.