Electronic structure and magnetic properties of oxygen deficient low-index surfaces of SnO2

Abstract In order to elucidate the origin of the observed ferromagnetism in SnO 2 nano-particles and films, we systematically investigate the electronic structure and magnetic properties of the reduced (110), (100) and (101) surfaces of SnO 2 and study the role of singly charged oxygen vacancy (V O 1 + ) at (110), (100), (101) and (001) surfaces on the electronic structure and magnetic properties of SnO 2 by using first-principles calculation. The results show that the stable reduced (110), (100) and (101) surfaces of SnO 2 are nonmagnetic, which is similar to early published results, where one neutral O vacancy at the low-index surfaces of SnO 2 produce spin non-splitting defect states. By contrast, although V O 1 + at the (110), (100) and (101) surfaces of SnO 2 do not induce the magnetism, V O 1 + at the (001) surface of SnO 2 induce magnetic moment, which mainly originate from partially filled 5p orbitals of the reduced Sn atom and partially filled 2p orbitals of the O atoms around the reduced Sn atom. More importantly, the magnetic coupling between moments induced by two V O 1 + at the (001) surface of SnO 2 is ferromagnetic, and this coupling can be attributed to the p–p hybridization interaction involving polarized electrons. The last result supports the experimental evidence that the observed ferromagnetism in undoped SnO 2 originate from V O 1 + at the surfaces.