First-principles calculation of magnetoelastic coefficients and magnetostriction in the spinel ferrites CoFe2O4 and NiFe2O4

We present calculations of magnetostriction constants for the spinel ferrites CoFe₂O₄ and NiFe₂O₄ using density functional theory within the GGA+U approach. Special emphasis is devoted to the influence of different possible cation distributions on the B-site sublattice of the inverse spinel structure on the calculated elastic and magnetoelastic constants. We show that the resulting symmetry lowering has only a negligible effect on the elastic constants of both systems as well as on the magnetoelastic response of NiFe₂O₄, whereas the magnetoelastic response of CoFe₂O₄ depends more strongly on the specific cation arrangement. In all cases our calculated magnetostriction constants are in good agreement with available experimental data. Our work thus paves the way for more detailed first-principles studies regarding the effect of stoichiometry and cation inversion on the magnetostrictive properties of spinel ferrites.