Effects of electron-correlation, spin-orbit coupling, and modified Becke-Johnson potential in double perovskites SrLaBB′O6(B = Ni, Fe; B′ = Os, Ru)

We investigate the electronic and magnetic properties of the newly synthesized SrLaBB'O-6 (B = Ni, Fe; B' = Os, Ru) materials on the basis of density functional theory. Within local-density approximation (LDA), except for SrLaNiOsO6, the studied materials are found to be metallic. Inclusion of electron-correlation effects (U) and spin-orbit coupling (SOC) leads to the opening of the band gap at the Fermi level (E-F) for all the selected materials. Additionally modified Becke-Johnson (TB-mBJ) potential has been used which is found to enhance the band gap of 0.62 eV and 0.59 eV in SrLaNiOsO6 and SrLaNiRuO6, respectively while remains metallic for the SrLaFeOsO6. The magnetic ground state is found to be antiferromagnetic (AFM) for SrLaNiOsO6 and SrLaNiRuO6 consistent with the experimental observations. Replacing Ni by Fe in SrLaNiOsO6 resulted in SrLaFeOsO6. The ground state was found to be AFM. The co-operative effects of U and SOC opens a band gap ((similar to)0.03 eV) dictating the significant influence on SrLaFeOsO6. On the otherhand, the Mott-insulating state is observed with a band gap opening of 0.33 eV and 0.58 eV for SrLaNiOsO6 and SrLaNiRuO6, respectively with the dominant contributions from the Os-5d and Ru-4d bands at and around the Fermi level. The magnetic anisotropy suggests an easy axis along the [001]-direction. Charge ordering is found to be prominent in these compounds. Our result agrees well with the experimental findings.