Multiferroic phases of the frustrated quantum spin-chain compound linarite

TL;DR

This study investigates the dielectric and ferroelectric properties of linarite, a frustrated quantum spin-chain compound, revealing ferroelectricity in its low-field phase and spontaneous polarization in other phases, challenging existing models.

Contribution

It provides new experimental evidence of ferroelectricity in multiple magnetic phases of linarite, expanding understanding of its complex multiferroic behavior.

Findings

Ferroelectric character confirmed in low-field spin spiral phase

Spontaneous polarization detected in additional field-induced phases

Some polarization data incompatible with existing spin structure models

Abstract

The dielectric properties of the prototypical frustrated ferromagnetic spin-chain compound PbCuSO$_4$(OH)$_2$ known as linarite, are studied across its strongly anisotropic magnetic phase diagram in single crystal samples. The ferroelectric character of the principal low-field spin spiral phase is confirmed. The measured polarization is fully consistent with the previously proposed magnetic structure. Spontaneous polarization is also detected in two other field-induced phases but in some cases is incompatible with previously suggested models for the spin arrangement.