  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.
