Strain dependencies of energetic, structural, and polarization properties in tetragonal (PbTiO3)1/(SrTiO3)1 and (BaTiO3)1/(SrTiO3)1 superlattices: a comparative study with bulks

TL;DR

This study uses first-principles calculations to compare how strain affects ferroelectric, structural, and polarization properties in PbTiO3/SrTiO3 and BaTiO3/SrTiO3 superlattices versus their bulk counterparts, revealing distinct physics in superlattice formations.

Contribution

It provides a detailed comparative analysis of strain-dependent properties in superlattices and bulk materials, highlighting differences in ferroelectric behavior and interface effects.

Findings

Strain influences ferroelectric polarization and piezoelectric coefficients.

Superlattices exhibit different polarization dispersion structures compared to bulk materials.

Interface effects significantly alter the structural and electronic properties under strain.

Abstract

First-principles density functional calculations are performed to investigate the interplay between inplane strains and interface effects in 1by1 PbTiO3/SrTiO3 and BaTiO3/SrTiO3 superlattices of tetragonal symmetry. One particular emphasis of this study is to conduct side-by-side comparisons on various ferroelectric properties in short-period superlattices and in constituent bulk materials, which turns out to be rather useful in terms of obtaining valuable insight into the different physics when ferroelectric bulks form superlattices. The various properties that are studied in this work include the equilibrium structure, strain dependence of mixing energy, microscopic ferroelectric off-center displacements, macroscopic polarization, piezoelectric coeffcients, effective charges, and the recently formulated k-dependent polarization dispersion structure. The details of our findings are rather lengthy, and are summarized in Sec. IV.