Observation of a new incommensurate phase in the spinel MnV2O4

Using x-ray scattering, we studied the temperature dependence of a large volume of reciprocal space in a MnV2O4 spinel crystal. In addition to the known cubic to tetragonal phase transition at around 56 K, we observed previously unreported incommensurate modulation peaks at delta q = 0.33 0.33 -0.16. We measured the temperature dependence of these modulations and, while they exhibit a shift or splitting in momentum space analogous to that of the structural phase transition, they do so at higher temperature than the Bragg reflections (~100K). Our results suggest that MnV2O4 has an additional phase transition that may a precursor for the V t2g orbital ordering, which is closely related to the cubic to tetragonal transition.