Ferroelectric polarization flop in a frustrated magnet MnWO$_4$ induced by magnetic fields

TL;DR

This study reveals how magnetic fields can induce a polarization flop in MnWO4, linking magnetic order to ferroelectric properties and demonstrating a field-induced switch in polarization direction.

Contribution

It demonstrates a magnetic-field-induced polarization flop in MnWO4, a simple system without rare-earth f-moments, highlighting the role of noncollinear spin configurations.

Findings

Electric polarization appears in an elliptical spiral spin phase.

A polarization flop from b to a direction occurs above 10T magnetic field.

The noncollinear spin structure is key to ferroelectricity.

Abstract

The relationship between magnetic order and ferroelectric properties has been investigated for MnWO$_4$ with long-wavelength magnetic structure. Spontaneous electric polarization is observed in an elliptical spiral spin phase. The magnetic-field dependence of electric polarization indicates that the noncollinear spin configuration plays a key role for the appearance of ferroelectric phase. An electric polarization flop from the b direction to the a direction has been observed when a magnetic field above 10T is applied along the b axis. This result demonstrates that an electric polarization flop can be induced by a magnetic field in a simple system without rare-earth f-moments.