Coupling of magnetic and ferroelectric hysteresis by a multi-component magnetic structure in Mn2GeO4

TL;DR

This paper demonstrates that Mn2GeO4 exhibits coupled ferroelectricity and ferromagnetism through complex magnetic structures, revealing a new pathway for multifunctional magnetic-ferroelectric materials.

Contribution

It uncovers the direct coupling mechanism between ferroelectricity and ferromagnetism mediated by Dzyaloshinskii-Moriya interactions in Mn2GeO4.

Findings

Ferroelectric polarization and ferromagnetic magnetization are directly coupled.

A spin spiral generates ferroelectricity, while canted order causes weak ferromagnetism.

Dzyaloshinskii-Moriya interactions mediate the coupling.

Abstract

The olivine compound Mn2GeO4 is shown to feature both a ferroelectric polarization and a ferromagnetic magnetization that are directly coupled and point along the same direction. We show that a spin spiral generates ferroelectricity (FE), and a canted commensurate order leads to weak ferromagnetism (FM). Symmetry suggests that the direct coupling between the FM and FE is mediated by Dzyaloshinskii-Moriya interactions that exist only in the ferroelectric phase, controlling both the sense of the spiral rotation and the canting of the commensurate structure. Our study demonstrates how multi-component magnetic structures found in magnetically-frustrated materials like Mn2GeO4 provide a new route towards functional materials that exhibit coupled FM and FE.