First-principles study of electronic structure and magnetic properties of doped SnO2 (rutile) with single and double impurities

Using the augmented spherical wave method, the electronic structure and magnetic properties of the rutile SnO2 doped with single and double impurities: Sn1-xMnxO2, Sn1-xWxO2, and Sn1-2xMnxWxO2 with x=0.0625, have been studied. The scalar-relativistic implementation with a generalized gradient approximation functional has been used for treating the effects of exchange and correlation. The ground state of Mn-, and W-doped SnO2 systems have a total magnetic moments of 3 and 2 mu(B), respectively. The half-metallic nature appears in Sn1-2xMnxWxO2, which makes them suitable as spintronic systems with total magnetic moment of 5 mu(B). The advantages of doping SnO2 with double impurities are investigated in this work. The total moment of the system, the local magnetic moments of the impurities, and their oxidation states are also discussed. Since there are two possible couplings between the impurities, we studied both configurations (ferromagnetic and antiferromagnetic) for double-impurities-doped SnO2. Magnetic properties and interatomic exchange have been computed for various distances between Mn and W. The indirect exchange between double impurities has similarities with the Zener mechanism in transition metal oxides. Based on the interaction between localized moments, via hybridization between impurities orbitals with the host oxygen, a double exchange mechanism is proposed to explain the ferromagnetism of our system. (C) 2011 Elsevier B.V. All rights reserved.