Computational modeling of the defect structure, hyperfine and magnetic properties of the Mn2+-doped magnetite of the composition MnxFe3-yO4 (y = ⅔ x)

Abstract

The defect structure, hyperfine and magnetic properties of Mn2+-doped Fe3O4 of the composition MnxFe3-yO4(y=⅔x) are modeled using atomistic and DFT calculations. The atomistic simulations show the substitution of the Mn2+ ions for Fe3+ ones at the tetrahedral sites to be energetically favorable than their substitution at the octahedral sites. These Mn2+ impurities are charge-balanced by the occupation of either Mn2+ or Fe 3+ ions of interstitial tetrahedral sites. The method of GGA with on-site Coulomb interaction approximation for the exchange-correlation potential is used to calculate the electronic structure, hyperfine and magnetic moments of the structurally most preferred models. The results obtained show the model in which all the Mn2+ ions substitute for tetrahedral Fe 3+ ions with Fe3+ ions expelled to interstitial tetrahedral sites to be consistent with the observed experimental trends of the hyperfine and magnetic properties.