Abstract
The electronic structure and magnetic properties of pseudo-cubic and tetragonal double perovskite oxides Sr2MnNbO6, Sr2FeMoO6 and Sr2NiRuO6, have been determined by using the full potential linear augmented plane wave method (FP-LAPW) employing the LSDA + U scheme. The spin-orbit coupling (SOC) has been taken into consideration. These calculations showed that all the three compounds in their two crystalline structures are half metallic. The values of the total energy have indicated that first two compounds prefer the tetragonal structures while the third one prefers the pseudo-cubic structure. The obtained magnetic moments indicate that Sr2MnNbO6 and Sr2NiRuO6 are ferromagnetic while Sr2FeMoO6 has ferrimagnetic ordering. The effect of the spin-orbit coupling was seen to grow from quenched to weakly unquenched to unquenched as going from Nb to Ru and from Mn to Ni as signified by the values of the orbital magnetic moments of the 3d and 4d orbitals. Sr2NiRuO6 shows half-metallic conduction and ferromagnetism in accordance with the superexchange interaction e(g)(2) - 0 - e(g)(0) Goodenough-Kanamori-Anderson (GKA). (C) 2010 Elsevier B.V. All rights reserved.