Electronic Structure and Magnetic Phase Transition in Double Perovskite La_2-xNa_xMnMoO₆ (x=0, 0.5, 1.0, 1.5, 2.0)

Recent research are focused on perovskite materials because of their interesting properties. Among others, double perovskites La_2-xNa_xMnMoO₆ shows magnetocaloric effect and large magnetoresistance making it appropriate substance for magnetic refrigeration applications at room temperature. Here, we investigate the electronic and magnetic properties of this recently synthesized material. We found that consistent with the experiment, for x=1.5, a ferromagnetic (FM) ground state is observed. With increase in La concentration, the charge transfers to Mn and Mo sites with increasing moment. It is interesting to note that magnetic phase transition occurs when doping concentration varies for x≤1. The electronic behavior shows metallic with major contribution from Mo-4d on Fermi level. The calculated net magnetic moment is 5.78 Bohr magneton which is in good agreement with the experimental value of 5.55 Bohr magneton. Our results reveals that interaction between the nearest neighbor and next nearest neighbor among Mn³⁺(t_2g³e_g¹) and Mo⁵⁺(t_2g¹e_g⁰) ions on the octahedral sites shows ferromagnetic coupling for x>1.