We present low-temperature x-ray diffraction, susceptibility, specific heat, and thermal conductivity results both on single crystal and polycrystalline $\mathrm{Mn}{\mathrm{V}}_2{\mathrm{O}}_4$. The single crystal sample exhibits two transitions: a spin ordering (ferrimagnetic) transition at $T_{\mathrm{SO}}=56\mathrm{K}$ and an orbital ordering transition at $T_{\mathrm{OO}}=52\mathrm{K}$. The structural change and phase separation at $T_{\mathrm{OO}}$ suggest that the transition is first order. With applied magnetic fields, both $T_{\mathrm{SO}}$ and $T_{\mathrm{OO}}$ increase and $T_{\mathrm{OO}}$ disappears with $H⩾0.5\mathrm{T}$. The polycrystalline sample just exhibits one transition at $55\mathrm{K}$. The difference between the single crystal and polycrystalline samples is due to the nonstoichiometric polycrystalline sample.

• Received 11 June 2007

DOI:https://doi.org/10.1103/PhysRevB.76.174403