Magnetic structure and magnetoelectric coupling in bulk and thin film FeVO$_4$

TL;DR

This study investigates the magnetoelectric properties of FeVO$_4$, revealing strong spin-charge coupling, a model for magnetoelectric interaction, and experimental evidence of electric field influence on phase transition and dielectric behavior.

Contribution

The paper presents a symmetry-based model for magnetoelectric coupling in FeVO$_4$ and experimentally demonstrates electric field effects on its multiferroic phase transition in thin films.

Findings

Electric field increases the phase transition temperature by 0.25 K at 4 MV/m.

Significant magnetodielectric shift observed, enhanced by magnetic order.

Magnetoelectric phase diagram of FeVO$_4$ is constructed.

Abstract

We have investigated the magnetoelectric and magnetodielectric response in FeVO$_4$, which exhibits a change in magnetic structure coincident with ferroelectric ordering at $T_{N2}$$\approx$15 K. Using symmetry considerations, we construct a model for the possible magnetoelectric coupling in this system, and present a discussion of the allowed spin structures in FeVO$_4$. Based on this model, in which the spontaneous polarization is caused by a trilinear spin-phonon interaction, we experimentally explore the magnetoelectric coupling in FeVO$_4$ thin films through measurements of the electric field induced shift of the multiferroic phase transition temperature, which exhibits an increase of 0.25 K in an applied field of 4 MV/m. The strong spin-charge coupling in \fvo\, is also reflected in the significant magnetodielectric shift, which is present in the paramagnetic phase due to a quartic spin-phonon interaction and shows a marked enhancement with the onset of magnetic order which we attribute to the trilinear spin-phonon interaction. We observe a clear magnetic field induced dielectric anomaly at lower temperatures, distinct from the sharp peak associated with the multiferroic transition, which we tentatively assign to a spin reorientation cross-over. We also present a magnetoelectric phase diagram for FeVO$_4$.