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Contributed by Karin M. Rabe, October 14, 2019 (sent for review May 17, 2019; reviewed by Steven May and Silvia Picozzi)
Significance
Charge-order–driven ferroelectrics are an emerging class of materials with promise for high-frequency electron-dominated polarization switching, distinct from conventional ferroelectrics. However, only a few systems exhibiting this behavior have been experimentally realized thus far. With continued development of layer-by-layer growth techniques with a high level of composition control, the exploration of charge-ordered ferroelectrics can be extended to artificially structured superlattices. Here, we use density-functional theory to explore an experimentally realized bulk perovskite iron-oxide solid solution with robust charge ordering and find that in superlattices formed by layered cation ordering, bulk charge ordering is maintained and can lead to charge-order–driven ferroelectricity. Our results suggest that other broad classes of mixed valence materials may be promising candidates for discovery of electronic ferroelectrics.
Abstract
Charge-order–driven ferroelectrics are an emerging class of functional materials, distinct from conventional ferroelectrics, where electron-dominated switching can occur at high frequency. Despite their promise, only a few systems exhibiting this behavior have been experimentally realized thus far, motivating the need for new materials. Here, we use density-functional theory to study the effect of artificial structuring on mixed-valence solid-solution La1/3Sr2/3FeO3 (LSFO), a system well studied experimentally. Our calculations show that A-site cation (111)-layered LSFO exhibits a ferroelectric charge-ordered phase in which inversion symmetry is broken by changing the registry of the charge order with respect to the superlattice layering. The phase is energetically degenerate with a ground-state centrosymmetric phase, and the computed switching polarization is 39 μC/
Footnotes
- ↵1To whom correspondence may be addressed. Email: kmrabe{at}physics.rutgers.edu.
Author contributions: S.Y.P., K.M.R., and J.B.N. designed research; S.Y.P. performed research; and S.Y.P., K.M.R., and J.B.N. wrote the paper.
Reviewers: S.M., Drexel University; and S.P., Consiglio Nazionale delle Ricerche - SuPerconducting and other INnovative materials and devices institute (CNR-SPIN).
The authors declare no competing interest.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1906513116/-/DCSupplemental.
Published under the PNAS license.
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Superlattice-induced ferroelectricity in charge-ordered La1/3Sr2/3FeO3
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