Pressure-Temperature Phase Diagram of Multiferroic $Ni_3V_2O_8$

TL;DR

This study maps the pressure-temperature phase diagram of the multiferroic Ni3V2O8, revealing how hydrostatic pressure suppresses its ferroelectric phase and identifying critical pressures and associated lattice anomalies.

Contribution

It provides the first detailed pressure-temperature phase diagram of Ni3V2O8, showing how pressure affects its multiferroic phases and lattice properties.

Findings

Ferroelectric phase stability decreases with pressure.

Ferroelectricity is suppressed at 1.64 GPa.

Anisotropic lattice anomalies occur at phase transitions.

Abstract

The pressure-temperature phase diagram of multiferroic $Ni_3V_2O_8$ is investigated for hydrostatic pressures up to 2 GPa. The stability range of the ferroelectric phase associated with the incommensurate helical spin order is reduced by pressure and ferroelectricity is completely suppressed at the critical pressure of 1.64 GPa at 6.2 K. Thermal expansion measurements at ambient pressure show strong step-like anomalies of the lattice parameters associated with the lock-in transition into the commensurate paraelectric phase. The expansion anomalies are highly anisotropic, the related volume change is consistent with the high-pressure phase diagram.