Strain-induced isosymmetric ferri-to-ferroelectric transition with large piezoelectricity

TL;DR

This paper predicts a strain-induced isosymmetric transition in certain superlattices that enables large piezoelectric responses, offering a new route to high-performance ferroelectric materials without chemical disorder.

Contribution

It reports a novel ferroic transition in superlattices driven by epitaxial strain, leading to large piezoelectricity without changing symmetry.

Findings

Epitaxial strains less than 2% induce the transition.

Electric polarization increases by ~5X across the phase boundary.

Large electromechanical response up to 131 pC/N predicted near the transition.

Abstract

We identify a first-order, isosymmetric transition between a ferrielectric (FiE) and ferroelectric (FE) state in $A$-site ordered LaScO$_{3}$/BiScO$_{3}$ and LaInO$_{3}$/BiInO$_{3}$ superlattices. Such a previously unreported ferroic transition is driven by the easy switching of cation displacements without changing the overall polarization direction or crystallographic symmetry. Epitaxial strains less than 2% are predicted to be sufficient to transverse the phase boundary, across which we capture a ~5X increase in electric polarization. In a fashion similar to classic Pb-based perovskite ceramics with a morphotropic phase boundary (MPB), we predict a large electromechanical response up to 131 pC/N in the vicinity of FiE-FE phase boundary. We propose this transition as alternative ferroic transition to obtain large piezoelectricity, with the additional advantage of operating under extreme conditions in benign chemistries and without chemical disorder.