Role of defects in magnetic properties of Fe-doped SnO₂ films fabricated by the Sol--Gel method

This paper obtains the room temperature ferromagnetism in Sn_1-xFe_xO₂ films fabricated by the Sol--Gel method. X-ray diffraction results show that Fe doping inhibits the growth of SnO₂ and Fe³⁺ ions occupy the Sn sites. The measurement of resistance excludes the free carrier inducing ferromagnetism. Moreover, the temperature dependence of magnetization has been better fitted by the Curie--Weiss law and bound magnetic polaron (BMP) theory. An enhancement of ferromagnetism is achieved by annealing the samples with x=7.1% in H₂, and a decrease of oxygen flow rate. All these results prove that the BMP model depending on defects can explain ferromagnetism in diluted magnetic oxides.