Dimensionality-induced change in topological order in multiferroic oxide superlattices

Abstract

We construct ferroelectric ðLuFeO3Þm=ðLuFe2O4Þ superlattices with varying index m to study the effect of confinement on topological defects. We observe a thickness-dependent transition from neutral to charged domain walls and the emergence of fractional vortices. In thin LuFeO3 layers, the volume fraction of domain walls grows, lowering the symmetry from P63cm to P3c1 before reaching the nonpolar P63=mmc state, analogous to the group-subgroup sequence observed at the high-temperature ferroelectric to paraelectric transition. Our study shows how dimensional confinement stabilizes textures beyond those in bulk ferroelectric systems.