Defect driven ferromagnetism in SnO2: a combined study using density functional theory and positron annihilation spectroscopy

Abstract

Room temperature ferromagnetic ordering has been observed in a high purity polycrystalline SnO₂ sample due to irradiation of 96 MeV oxygen ions. Ab initio density functional theory calculation indicates that tin vacancies are mainly responsible for inducing the magnetic moment in SnO₂ whereas oxygen vacancies in SnO₂ do not contribute any magnetic moment. Positron annihilation spectroscopy has been employed to characterize the chemical identity of irradiation generated defects in SnO₂. Results indicate the dominant presence of Sn vacancies in O ion irradiated SnO₂. The irradiated sample turns out to be ferromagnetic at room temperature.