Thermal expansion and pressure effect in MnWO4

TL;DR

This study investigates how thermal expansion and hydrostatic pressure influence the magnetic and ferroelectric phases of MnWO4, revealing anisotropic lattice anomalies and pressure-induced stabilization of the paraelectric phase.

Contribution

It provides new insights into the pressure effects on MnWO4's ferroelectric and magnetic phases through thermal expansion and dielectric measurements.

Findings

Anisotropic lattice anomalies at 7.8 K indicating magnetic transition

Hydrostatic pressure stabilizes the paraelectric phase

Pressure reduces the stability range of the ferroelectric phase

Abstract

MnWO4 has attracted attention because of its ferroelectric property induced by frustrated helical spin order. Strong spin-lattice interaction is necessary to explain ferroelectricity associated with this type of magnetic order.We have conducted thermal expansion measurements along the a, b, c axes revealing the existence of strong anisotropic lattice anomalies at T1=7.8 K, the temperature of the magnetic lock-in transition into a commensurate low-temperature (reentrant paraelectric) phase. The effect of hydrostatic pressure up to 1.8 GPa on the FE phase is investigated by measuring the dielectric constant and the FE polarization. The low- temperature commensurate and paraelectric phase is stabilized and the stability range of the ferroelectric phase is diminished under pressure.