Magnetic Field Tuning of Magnetic- and Structure-Phase Transition in Mn2V2O7 Crystals

Transition metal-vanadium oxides Mn2V2O7 have recently attracted much interest due to its rich structural and magnetic phase transition. However, the systematic studies on the effects of magnetic field (H) on these phase transitions are still not available. Here, based on the high-quality Mn2V2O7 crystals, the effects of the magnetic field on its phase transitions were systematically studied. When applied H is aligned along the [110] direction of beta-Mn2V2O7, there is a spin-flop transition at low temperature (<17 K). The magnetic field-temperature magnetic phase diagram is proposed. In addition, the magneto-crystalline anisotropic energy of Mn(2)V(2)O(7)7 shows the unconventional "dome-like" feature, reaching its maximum at 11 K, which may be related to the commensurate-incommensurate magnetic phase transition determined by neutron scattering previously. At the martensitic transformation around 270 K, 1 T H aligned along the [110] direction can induce the 1-2 K temperature shift of martensitic transformation, simultaneously leading to a cusp-like dielectric constant change (the maximum magneto-dielectric effect similar to -18%). Transition-temperature shift induced by H can be quantitatively understood by thermodynamic Clausius-Clapeyron relation. These results substantiate that the magnetic field has pronounced effects on the phase transition in Mn2V2O7.