Magnetoelectric coupling and decoupling in multiferroic hexagonal YbFeO3 thin films

TL;DR

This study investigates the magnetoelectric coupling in hexagonal YbFeO3 thin films, revealing bulk decoupling and potential domain-wall coupling, with implications for electric field control of magnetic states.

Contribution

It provides experimental evidence and theoretical analysis of magnetoelectric decoupling and domain-wall coupling in hexagonal YbFeO3, a prototypical multiferroic material.

Findings

Bulk ME decoupling observed via XMCD measurements.

Higher energy barrier for ME-coupled switching path.

Possible domain-wall ME coupling related to ferroelectric domain walls.

Abstract

The coupling between ferroelectric and magnetic orders in multiferroic materials and the nature of magnetoelectric (ME) effects are enduring experimental challenges. In this work, we have studied the response of magnetization to ferroelectric switching in thin-film hexagonal YbFeO3, a prototypical improper multiferroic. The bulk ME decoupling and potential domain-wall ME coupling were revealed using x-ray magnetic circular dichroism (XMCD) measurements with in-situ ferroelectric polarization switching. Our Landau theory analysis suggests that the bulk ME-coupled ferroelectric switching path has a higher energy barrier than that of the ME-decoupled path; this extra barrier energy is also too high to be reduced by the magneto-static energy in the process of breaking single magnetic domains into multi-domains. In addition, the reduction of magnetization around the ferroelectric domain walls predicted by the Landau theory may induce the domain-wall ME coupling in which the magnetization is correlated with the density of ferroelectric domain walls. These results provide important experimental evidence and theoretical insights into the rich possibilities of ME couplings in hexagonal ferrites, such as manipulating the magnetic states by an electric field.