Effect of Cationic Disorder on the Magnetic Moment of Sr₂FeMoO₆: Ab Initio Calculations

Abstract

Discrepancies between both theoretical calculations and experimental measurements of the magnetic moment on Fe sites in Sr 2 FeMoO 6 have been accounted for because of disorder effects. In this work, we deepen the repercussions of cationic disorder in the above ferromagnetic compound specially about the interactions between Fe antisites, which are found antiferromagnetic for the most stable systems. An amount of disorder (12.5% and 25%) was introduced within the systems via atomic substitution. Ab initio calculations using the generalized gradient approximation were performed with local Hubbard terms U Fe and U Mo associated with both Fe and Mo sites, respectively. We found a magnetic saturation of 2.99 μ B for a 12.5% amount of disorder and 2.22 μ B in the case of 25% disorder, which is in agreement with neutron magnetic scattering experiments. Half-metallicity is found to remain only for the 12.5% disorder case.