Toroidal moments as indicator for magneto-electric coupling: the case of BiFeO_3 versus FeTiO_3

TL;DR

This paper investigates how toroidal moments relate to structural modes in R3c-distorted perovskites, revealing their role in magneto-electric coupling, especially in multiferroic BiFeO_3 and FeTiO_3, with implications for electric field control of magnetization.

Contribution

It provides a detailed analysis of magnetic toroidal moments considering localized magnetic moments and structural distortions, clarifying their role in magneto-electric coupling in specific perovskites.

Findings

Toroidal moments can be evaluated considering oxygen site magnetic moments.

Structural distortions influence the coupling between magnetization and electric polarization.

FeTiO_3 shows potential for electric field-induced magnetization switching.

Abstract

In this paper we present an analysis of the magnetic toroidal moment and its relation to the various structural modes in R3c-distorted perovskites with magnetic cations on either the perovskite A or B site. We evaluate the toroidal moment in the limit of localized magnetic moments and show that the full magnetic symmetry can be taken into account by considering small induced magnetic moments on the oxygen sites. Our results give a transparent picture of the possible coupling between magnetization, electric polarization, and toroidal moment, thereby highlighting the different roles played by the various structural distortions in multiferroic BiFeO_3 and in the recently discussed isostructural material FeTiO_3, which has been predicted to exhibit electric field-induced magnetization switching.