Interplay of trimerization, chirality and ferroelecticity in multiferroic BaCoSiO4

TL;DR

This paper develops a quantitative Landau free energy model for BaCoSiO4, a multiferroic material, capturing the interactions between trimerization, chirality, and ferroelectricity, and explaining experimental observations of domain walls and vortices.

Contribution

It introduces a first-principles derived Landau free energy model for multiferroic BaCoSiO4, elucidating the interplay of structural modes and ferroelectricity.

Findings

Quantitative model for domain walls and vortices

First-principles coefficients for free energy terms

Insight into multiferroic interactions in BaCoSiO4

Abstract

Multiferroic materials combine multiple ferroic orders that may enable cross-functionalities, e.g. control of one ferroic order by the field conjugate to the other one. BaCoSiO$_4$, a recently proposed multiferroic combines multiple unit cell-tripling modes, structural chirality and ferroelectric polarization, whose interactions result in a peculiar ground state. We derive the Landau free energy for interacting trimerization, electric polarization and structural chiral modes and find the corresponding coefficients from first-principles calculations. This results in a quantitative model for the description of domain walls and vortices, observed in recent experiments.