First-principles study of electron doping and disorder effects on electronic and magnetic properties in Sr2−xNdxFeMoO6 double perovskites

We have investigated the electronic and magnetic properties of electron-doped Sr2−xNdxFeMoO6 ( x = 0.0 , 0.25 , 0.5 ) using first-principles density functional theory within the generalized gradient approximation (GGA) and GGA + U schemes. Our results reveal that the structural-phase transition occurs for the composition x = 0.5 and the unit cell volume remains nearly constant from x = 0.0 to x = 0.25 . The magnetic moment of the Mo site increases distinctly on electron doping and the doped electrons are considered to occupy mainly the down-spin Mo 4d band from the band calculation. We also have performed the electronic structure calculations for pure and doped Sr2FeMoO6 with positional disorder at the Fe/Mo sites. Disordering is found to destroy the half-metallic nature of the ordered compound; moreover, disorder leads to a significant reduction in the net magnetic moment. It is found that the rapid reduction in the magnetic moment is mainly caused by the antiferromagnetic interaction between Fe–O–Fe and the electron doping effects.