First-principles study of structural, electronic and magnetic properties of double perovskite oxides Ba2CoMO6 (M=Mo and W)

Ba2CoMO6 (M=Mo and W) ordered double perovskite oxides have been investigated by using the first-principles of full potential linearized muffin-tin orbital (FP-LMTO) computational method. The structural, electronic and magnetic properties of Ba2CoMO6 were calculated using both the local spin density approximation (LSDA) and generalized gradient approximation (GGA) methods. The room temperature crystal structures of Ba2CoMO6 are face-centered cubic (space group Fm3¯m and tilt system a0a0a0) with lattice constants of (a=8.011 Å) and (a=8.031 Å) for (M=Mo) and (M=W), respectively. The crystals of Ba2CoMO6 contain alternating CoO6 and MO6 octahedra, almost fully ordered in the basal ab planes. It was shown that the obtained lattice constants agree well with the experimental data. The influence of M-cation on structural, electronic and magnetic properties of Ba2CoMO6 compounds is analyzed. The total and partial densities of states (DOSs) and partial and total spin magnetic moments are calculated, and the valence states of Co and M ions are examined. The magnetic and electronic properties and bond valence sums are consistent with the electronic configuration Co2+ (3d7)–M6+ (4d/5d)0 with Co2+ in high spin states.