Electrically driven octahedral rotations in SrTiO3 and PbTiO3

TL;DR

This study uses first-principles calculations to explore how electric fields influence oxygen octahedral rotations in SrTiO3 and PbTiO3, revealing complex phase diagrams and boundaries between rotational states.

Contribution

It introduces a detailed phase diagram of octahedral rotations under electric fields in SrTiO3 and PbTiO3 using a Landau-Devonshire model derived from first-principles data.

Findings

Rich phase diagrams of rotations versus electric field in both materials

Distinct differences in rotational behavior between SrTiO3 and PbTiO3

Identification of phase boundaries between different rotational states

Abstract

We investigate the oxygen octahedral rotations that occur in two perovskites, SrTiO3 and PbTiO3, as a function of applied three-dimensional electric displacement field, allowing us to map out the phase diagram of rotations in both the paraelectric and ferroelectric regions of the polar response. First-principles calculations at fixed electric displacement field are used to extract parameters of a Landau-Devonshire model that is analyzed to identify the phase boundaries between different rotational states. The calculations reveal a rich phase diagram of rotations versus applied field in both SrTiO3 and PbTiO3, although the details are quite different in the two cases.