Self-consistent (DFT + U) study of electronic, structural and magnetic properties in A₂NiMoO₆(A = Ba, Sr) compounds

This work aims to study the double perovskites A2NiMoO6 (A = Ba, Sr) by using the first principle calculation, within the framework of the self-consistent Hubbard correction. The value of this correction, for Ni and Mo depends strongly on the type of the studied compounds. Such values are determinate as 7.35 eV for Ni and 5.42 eV for Mo in the compound Ba2NiMoO6, whereas in the case of Sr2NiMoO6 the calculated values are 8.71 eV and 5.48 eV for Ni and Mo compound respectively. Based on the densities of state calculation we show that both the compounds are semiconductors with gap energies of 2.20 eV and 2.10 eV for Ba2NiMoO6 for Sr2NiMoO6, respectively. The total energies comparison shows clearly that the ground state is G-type anti-ferromagnetic order in agreement with experimental results, the magnetic interactions are due to the super-exchange mechanism acting in long range via hybridization throw Ni-O-Mo-O-Ni path.