Search for ferromagnetism in SnO2 doped with transition metals (V, Mn, Fe, and Co)

Abstract

Based on first-principles calculations, we have investigated electronic structures and magnetic propertiesof SnO2 doped with V, Mn, Fe, and Co. Our results show that ferromagnetism is the ground stateand that the Curie temperatures are expected to have high values for Fe- and Co-dopedSnO2, which is in good agreement with the experimental observations (Ogale et al 2003 Phys. Rev.Lett. 91 077205; Coey et al 2004 Appl. Phys. Lett. 84 1332). However, in V- and Mn-dopedSnO2, paramagnetism is more stable than ferromagnetism. In addition, we alsoprobe the effect of an oxygen vacancy. The results exhibit that an oxygenvacancy strongly influences the magnetic properties of these doped systems, andan oxygen vacancy strongly attracts Fe and Co ions. As a result, transitionmetal–oxygen vacancy–transition metal groups will be common in Fe- and Co-dopedSnO2, but this tendency does not exist in the cases of V and Mn doping. In V-dopedSnO2, ferromagnetism becomes more stable than antiferromagnetism afterinducing additional n-type carriers and the Curie temperature increases withincreasing density of n-type carriers. Hence, raising the density of n-typecarriers is a practical way to realize high Curie temperatures in V-dopedSnO2.