Ferromagnetism and half metallicity induced by oxygen vacancies in the double perovskite BaSrNiWO6: DFT study.

Using the spin polarized density functional theory (DFT) and exploring the Plane-Wave Self-Consistent Field (PWscf) code implemented in Quantum-ESPRESSO package, we investigate the effect of the Oxygen vacancies (V O ) and the Oxygen interstitial (O i ) on the double perovskite BaSrNiWO 6 . This deals with the magnetic ordering and the electronic structure in such a pure sample exhibiting the insulating anti-ferromagnetic (AFM) state. This study shows that the presence of oxygen deficient defects converts the insulating to half metal with ferromagnetic or anti-ferromagnetic states. The magnetic ordering in BaSrNiWO 6−δ depends on the position of the Oxygen vacancy in the unit cell. However, it has been shown that the Oxygen interstitial preserves the anti-ferromagnetic propriety. We have computed the formation energies of different positions of the Oxygen vacancy (V O ) and the Oxygen interstitial (O i ) in the BaSrNiWO 6 compound. We showed that the formation of V O is easier and vice versa for the O i formation. The obtained results reveal(V O ) and the Oxygen interstitial (O i ) that the anti-ferromagnetic can be converted to ferromagnetic in the double perovskite BaSrNiWO 6 induced by Oxygen vacancies V O . [ABSTRACT FROM AUTHOR]