Magnetic susceptibility and specific heat of a spinel MnV₂O ₄ single crystal

We investigated the magnetic and the thermodynamic properties of a spinel MnV₂O₄ single crystal. The magnetization and susceptibility show the signature of ferromagnetic ordering at ~61 K. A sharp peak in the magnetization and the specific heat indicate the structural phase transition at 58 K, consistent with the scattering experiments. The specific-heat data exhibits the signature of double transitions. In addition to the higher-temperature transition at T_S, the second transition occurs at a lower temperature T⊃*, which divides the phase below T _S into a low-magnetic-field and a high-magnetic-field phase. Based on the magnetic susceptibility and the specific heat, a wide-range temperature and magnetic-field phase diagram was constructed. The low-magnetic-field phase shows the characteristics of a spin-glass-like state. A comparison with the magnetic and thermodynamic characteristics of similar materials suggests that the low temperature and low-magnetic-field, spin-glass-like phase in MnV ₂O₄ may originate from the competition between the interchain and the intrachain exchange interaction owing to the fluctuating V-ion orbitals.