First-principles study of ferroelectric domain walls in multiferroic bismuth ferrite

TL;DR

This study uses first-principles density functional theory to analyze the structural, electronic, and magnetic properties of ferroelectric domain walls in multiferroic BiFeO3, revealing their stability, polarization behavior, and magnetic effects.

Contribution

It provides the first detailed first-principles analysis of ferroelectric domain walls in BiFeO3, identifying the most stable configurations and their electronic and magnetic characteristics.

Findings

109 degree domain wall has lowest energy

Domain walls show significant polarization change and potential steps

Magnetic moments are affected by bond angle changes at walls

Abstract

We present a first-principles density functional study of the structural, electronic and magnetic properties of the ferroelectric domain walls in multiferroic BiFeO3. We find that domain walls in which the rotations of the oxygen octahedra do not change their phase when the polarization reorients are the most favorable, and of these the 109 degree domain wall centered around the BiO plane has the lowest energy. The 109 degree and 180 degree walls have a significant change in the component of their polarization perpendicular to the wall; the corresponding step in the electrostatic potential is consistent with a recent report of electrical conductivity at the domain walls. Finally, we show that changes in the Fe-O-Fe bond angles at the domain walls cause changes in the canting of the Fe magnetic moments which can enhance the local magnetization at the domain walls.