Tunable ferroelectricity in oxygen-deficient perovskites

TL;DR

This study predicts that oxide perovskites with the Grenier structure and oxygen vacancies can exhibit tunable ferroelectricity, with polarization adjustable by selecting different rare-earth and alkaline-earth elements, promising for electronic applications.

Contribution

First-principles calculations demonstrate the potential for tunable ferroelectricity in oxygen-deficient Grenier phase perovskites with specific cation combinations.

Findings

Stable polar phases with tunable polarization identified.

Maximum polarization achieved with larger cations and small R elements.

Ferroelectricity driven by cooperative distortions of octahedral and tetrahedral units.

Abstract

Using first-principles calculations, we predict that tunable ferroelectricity can be realized in oxide perovskites with the Grenier structure and ordered oxygen vacancies. Specifically, we show that $R_{1/3}A_{2/3}\mathrm{FeO}_{2.67}$ solids (where $R$ is a rare-earth ion and $A$ an alkaline-earth cation) exhibit stable polar phases, with a spontaneous polarization tunable by an appropriate choice of $R$ and $A$. We find that larger cations combined with small $R$ elements lead to a maximum in the polarization and to a minimum in the energy barriers required to switch the sign of the polarization. Ferroelectricity arises from cooperative distortions of octahedral and tetrahedral units, where a combination of rotational and sliding modes controls the emergence of polarization within three-dimensional connected layers. Our results indicate that polar Grenier phases of oxide perovskites are promising materials for microelectronic applications and, in general, for the study of phenomena emerging from breaking inversion symmetry in solids.