Polarization Saturation in Strained Ferroelectrics

TL;DR

This study uses density-functional calculations to reveal a universal polarization saturation in strained ferroelectrics, caused by strong electron-ion correlation, indicating a fundamental limit to strain-induced polarization enhancement.

Contribution

It uncovers a previously overlooked strain regime where polarization saturates, demonstrating a universal phenomenon across multiple ferroelectric materials.

Findings

Polarizations saturate at large strains in PbTiO3, BaTiO3, SrTiO3

Saturation results from strong electron-ion correlation causing cancellation

Reveals a fundamental limit to strain-induced polarization enhancement

Abstract

Using density-functional calculations we study the structure and polarization response of tetragonal PbTiO3, BaTiO3 and SrTiO3 in a strain regime that is previously overlooked. Different from common expectations, we find that the polarizations in all three substances saturate at large strains, demonstrating a universal phenomenon. The saturation is shown to originate from an unusual and strong electron-ion correlation that leads to cancellation between electronic and ionic polarizations. Our results shed new insight on the polarization properties, and reveal the existence of a fundamental limit to the strain-induced polarization enhancement.