ab initio Study of Strain-Induced Ferroelectricity in SrTiO3

TL;DR

This study uses first-principles calculations to show that applying strain to SrTiO3 induces ferroelectricity and raises the Curie temperature, revealing nonlinear mode coupling effects.

Contribution

It introduces a new first-principles structure optimization method to analyze strain effects on ferroelectricity in SrTiO3.

Findings

Ferroelectricity is induced by strain.

Curie temperature increases with strain.

Strong nonlinear coupling between modes is observed.

Abstract

Valley lines on total-energy surfaces for the zone-center distortions of free-standing and in-plane strained SrTiO3 are investigated with a newly developed first-principles structure optimization technique [Jpn. J. Appl. Phys. vol.43 (2004), p.6785]. The results of numerical calculations confirmed that the ferroelectricity is induced, and the Curie temperature is increased, by applying biaxial compressive or tensile strains. Along the distortion, strong nonlinear coupling between the soft- and hard-modes is demonstrated.