Prediction of new low-energy phases of BiFeO$_3$ with large unit cell and complex tilts beyond Glazer notation

TL;DR

This paper uses density functional theory to discover new low-energy polar and non-polar phases of BiFeO3 with complex tilts beyond traditional notation, offering insights into stabilizing these phases for multiferroic applications.

Contribution

It identifies previously unknown low-energy phases of BiFeO3 with complex tilts and polarization directions, expanding the understanding of its structural diversity.

Findings

Discovery of new polar and non-polar BiFeO3 structures

Identification of non-centrosymmetric phases with unique polarization

Potential stabilization routes via strain and heterostructures

Abstract

Bismuth ferrite is one of the most widely studied multiferroic materials because of its large ferroelectric polarisation coexisting with magnetic order at room temperature. Using density functional theory (DFT), we identify several previously unknown polar and non-polar structures within the low-energy phase space of perovskite-structure bismuth ferrite, BiFeO$_3$. Of particular interest is a series of non-centrosymmetric structures with polarisation along one lattice vector, combined with anti-polar distortions, reminiscent of ferroelectric domains, along a perpendicular direction. We discuss possible routes to stabilising the new phases using biaxial heteroepitaxial strain or interfacial electrostatic control in heterostructures.