Pressure and magnetic field effects on ferroelastic and antiferromagnetic orderings in honeycomb-lattice Mn2V2O7

The multiferroic nature of the honeycomb-lattice $\mathrm{M}{\mathrm{n}}₂{\mathrm{V}}₂{\mathrm{O}}₇$ was investigated through detailed temperature, high-pressure, and magnetic-field-dependent measurements. A first-order martensiticlike structural phase transition with the thermal hysteresis associated with magnetic, heat-capacity, and dielectric anomalies was observed between ${T}_Mh$ (303 K) and ${T}_Mc$ (291 K). External pressure up to 15.41 kbar suppresses the thermal hysteresis in the magnetization data, indicating that the high-temperature \ensuremath{\beta}-phase persists down to the lower temperature under 15.41 kbar. Furthermore, isothermal capacitance-stress hysteresis loops along with crystallographic Aizu notation of $2/mF\overline{1}$ supports a martensitic phase transition driving ferroelastic ordering near or below room temperature. At low temperature, a long-range antiferromagnetic ordering was observed at ${T}_N\ensuremath{\sim}17\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. With increasing the external pressure up to 15.41 kbar, 100% enhancement of ${T}_N$ was observed and a metamagnetic transition at 5 K was enhanced near 3 T. High-field magnetization study up to 60 T induces multiple metamagnetic transitions below ${T}_N$. Below ${T}_N$, a magnetostriction induced magnetoelectric coupling was observed and further supported by the temperature-dependent x-ray studies. Taking these comprehensive research findings into account, we established that $\mathrm{M}{\mathrm{n}}₂{\mathrm{V}}₂{\mathrm{O}}₇$ is a unique multifunctional material with the coexistence of ferroelastic and antiferromagnetic orderings and with weak magnetoelectric coupling.