Orbital ordering and magnetic field effect in MnV2O4

We studied the structural properties of an orbital-spin-coupled spinel oxide, MnV2O4, mainly by single-crystal x-ray diffraction measurement. It was found that a structural phase transition from cubic to tetragonal and ferrimagnetic ordering occur at the same temperature (T-s,T-N=57 K). The structural phase transition was induced also by magnetic field above T-s. In addition, magnetic-field-induced alignment of tetragonal domains results in large magnetostriction below T-s. We also found that the structural phase transition is caused by the antiferro-type ordering of the V t(2g) orbitals.