Electronic and Magnetic Properties of 5d, 5d, and 5d Double Perovskites BaMOsO (M = K, Ca, and Sc): Ab Initio Study.

We perform detailed investigations on the electronic and magnetic properties in double perovskites BaMOsO (M = K, Ca, and Sc), with formal valences of Os (5d), Os (5d), and Os (5d), respectively, using first-principles calculations. To understand the effects of Coulomb interaction ( U), spin-orbit coupling (SOC), and magnetic order, we carry out different calculations within density functional theory. It is shown that SOC and U energy not only provide the magneto crystalline anisotropies but also significantly affect the size of the local moments and the magnetic structures in these compounds. The electronic configuration of 5d and 5d of Os in BaMOsO (M = K and Ca) have the metal-insulator transition (MIT) as the direction of the local moment changes, while the electronic structure of half-filled 5d orbitals of Os in BaScOsO is insulator, independent of the local moment direction. Our results indicate that both SOC and U interactions are necessary in enlarging the band gaps and putting these compounds into the MIT correlated insulators.