Prediction of low-energy phases of BiFeO3 with large unit cells and complex tilts beyond Glazer notation

Abstract

We use density functional theory to identify several previously unknown polar and nonpolar structures within the low-energy phase space of perovskite-structure bismuth ferrite, $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$. Bismuth ferrite is one of the most widely studied multiferroic materials because of its large ferroelectric polarization coexisting with magnetic order at room temperature. Of particular interest is a series of noncentrosymmetric structures with polarization along one lattice vector, combined with antipolar 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.