Exploration of uranium double perovskites Ba2MUO6 (M = Co, Ni) for magnetism, spintronic and thermoelectric applications

Ba2MUO6 (M = Co, Ni) alloys are investigated to understand their electronic structure, magnetic character together with thermoelectric behavior using ab-initio formulism. The variations in physical properties by changing M-site atom are analyzed. The crystal structure of Ba2MUO6 (M = Co, Ni) alloys is found to be face-centered cubic (Fm-3m) with lattice constant of 0.845 nm for Ba2CoUO6 and 0.841 nm for Ba2NiUO6. The band structure and density of states convey half-metallic ferromagnetic character of Ba2NiUO6, while Ba2NiUO6 exhibit ferromagnetic semiconducting nature. The electron filling in the d-orbitals of Co and Ni determines the overall electronic and magnetic character of alloys. The obtained structural parameters and magnetic moment are consistent with experimental results. The variation in various thermoelectric parameters with temperature is also examined. The highest value of power factor obtained for Ba2NiUO6 and Ba2CoUO6 is 54.92 mu W cm(-1) K-2 and 9.25 mu W cm(-1) K-2, respectively. The semiconducting nature in both spin orientations favors Ba2NiUO6 for thermoelectric applications. The computed elastic constants along with other elastic parameters suggest that these alloys are mechanically stable and possess ductile character.