Competing phases and domain structures of ferroelectric perovskites: the benefit of epitaxial (110) growth

TL;DR

This study uses first-principles molecular dynamics to explore how (110) epitaxial strain influences phase stability and domain structures in ferroelectric perovskite thin films, revealing diverse metastable states with high tunability.

Contribution

It demonstrates that (110) epitaxial strain can stabilize a variety of metastable nanoscale states in ferroelectric perovskites, surpassing the effects of traditional (100) growth orientations.

Findings

(110) strain stabilizes diverse metastable nanoscale states.

Multidomain configurations with various domain wall orientations are observed.

Complex superdomain patterns and antiferroelectric-like domains appear in PbTiO$_3$.

Abstract

Strain and domain engineering offer powerful routes to control phase and domain stability in ferroelectric thin films. While most studies have focused on (100)-oriented growth, the impact of lower-symmetry orientations remains underexplored. We address this gap in knowledge with first-principles based molecular dynamics simulation for the example of prototypical ferroelectric perovskites under (110) strain. Epitaxial (110) strains may indeed outperform the widely studied (100) orientation, as even modest strain values stabilize a diverse set of metastable nanoscale states with potential high functional tunability. In this regime, the films exhibit multidomain configurations with domain wall normal oriented along the clamped in-plane or the relaxed out-of-plane directions and heterophases in BaTiO$_3$ and KNbO$_3$. Besides, complex superdomain patterns and antiferroelectric-like domains are observed in PbTiO$_3$. These metastable nanoscale configurations may allow for large reversible responses.