Enhanced polarization in strained BaTiO$_3$ from first principles

TL;DR

This study uses first-principles calculations to show that compressive strain significantly enhances polarization in BaTiO$_3$, with potential implications for thin film applications on various substrates.

Contribution

It provides a quantitative analysis of polarization enhancement in BaTiO$_3$ under epitaxial strain using density functional theory, highlighting nearly 70% increase at high compressive strains.

Findings

Polarization increases with tetragonality under strain.

Maximum polarization enhancement of nearly 70%.

Results applicable to epitaxial thin films on different substrates.

Abstract

The structure, polarization, and zone-center phonons of bulk tetragonal BaTiO$_3$ under compressive epitaxial stress are calculated using density functional theory within the local density approximation. The polarization, computed using the Berry-phase formalism, increases with increasing tetragonality and is found to be enhanced by nearly 70% for the largest compressive misfit strain considered (-2.28%). The results are expected to be useful for the analysis of coherent epitaxial BaTiO$_3$ thin films and heterostructures grown on perovskite substrates having a smaller lattice constant, such as SrTiO$_3$.