Modeling functional piezoelectricity in perovskite superlattices with competing instabilities

TL;DR

This paper develops a predictive model for piezoelectricity in perovskite superlattices, accounting for competing instabilities, and demonstrates how functional piezoelectricity can be engineered through nonlinear effects and interface enhancements.

Contribution

It introduces an accurate, layer-specific model for piezoelectricity in superlattices with complex stacking and competing modes, advancing the understanding of functional piezoelectric materials.

Findings

Nonlinear piezoelectric effects observed in PbTiO₃/SrTiO₃ superlattices.

Interface enhancement of piezoelectricity in BaTiO₃/CaTiO₃ superlattices.

Model accurately predicts piezoelectric behavior in arbitrary superlattice stacking.

Abstract

Based on the locality principle of insulating superlattices, we apply the method of Wu {\it et al} [Phys. Rev. Letter {\bf 101}, 087610 (2008)] to the piezoelectric strains of individual layers under fixed displacement field. For a superlattice of arbitrary stacking sequence an accurate model is acquired for predicting piezoelectricity. By applying the model in the superlattices where ferroelectric and antiferrodistortive modes are in competition, functional piezoelectricity can be achieved. A strong nonlinear effect is observed and can be further engineered in the PbTiO$_3$/SrTiO$_3$ superlattice and an interface enhancement of piezoelectricity is found in the BaTiO$_3$/CaTiO$_3$ superlattice.