Multiferroicity and spiral magnetism in FeVO$_4$ with quenched Fe orbital moments

TL;DR

This study investigates FeVO$_4$, revealing its complex magnetic and ferroelectric phases, and highlights how quenched orbital moments influence multiferroicity and magnetic frustration in this material.

Contribution

It provides new insights into the role of quenched orbital moments and structural features in the multiferroic behavior of FeVO$_4$, a frustrated spiral magnet.

Findings

FeVO$_4$ exhibits two magnetic transitions at 22K and 15K.

Below 15K, FeVO$_4$ becomes weakly ferroelectric with non-collinear magnetic order.

The structure clarifies the influence of anisotropy and frustration on multiferroicity.

Abstract

FeVO$_4$ has been studied by heat capacity, magnetic susceptibility, electric polarization and single crystal neutron diffraction experiments. The triclinic crystal structure is made of \emph{S}-shaped clusters of six Fe$^{3+}$ ions, linked by VO$_4^{3-}$ groups. Two long-range magnetic ordering transitions occur at T$_{N1}$=22K and T$_{N2}$=15K. Both magnetic structures are incommensurate. That stable below T$_{N1}$ is collinear with amplitude modulated moments whereas below T$_{N2}$ the arrangement is non-collinear with a helicoidal modulation. Below T$_{N2}$, \fevo becomes weakly ferroelectric coincidentally with the loss of the collinearity of the magnetic structure. We conclude that \fevo provides another example of frustrated spiral magnet similar to the classical TbMnO$_3$ compound. However, \fevo has quenched orbital moments and a particular structure clarifying the respective role of anisotropy and magnetic frustration in this type of multiferroic materials.