Structural, elastic, electronic and magnetic properties of Ba₂XOsO₆ (X = Li, Na, Ca) double perovskites

The double perovskite oxides have diverse applications in the fields such as magnetism and spintronics. We report on the structural, elastic, electronic and magnetic properties of double perovskites Ba₂XOsO₆ (X = Li, Na, Ca) calculated using the full-potential linearized augmented plane wave method. For the treatment of the exchange–correlation energy, the generalized gradient approximation (GGA) of Wu and Cohen (WC-GGA), Perdew, Burke and Ernzerhof (PBE-GGA), Engel-Vosko’s (EV-GGA) and GGA plus Hubbard U parameter (GGA+U) have been utilized. The calculated lattice constant, band structure and density of states are found in good agreement with the existing experimental and theoretical results. In particular, we present theoretical calculation of the bulk modulus of these compounds which, according to our knowledge, has not been reported. The calculation of elastic parameters suggests that these compounds possess ductile nature. The GGA+U approach provides better band gap results as compared to others approximations. The density of states shows that Ba-5p, Ba-4f, Os-5d and O-2p states contribute majorly in the conduction and valence bands. The calculated magnetic moments of all these compounds reveal ferromagnetic nature. These compounds seem to possess half-metallic properties which may make them useful candidates for spintronics device applications.