期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2019
卷号：116
期号：48
页码：23972-23976
DOI：10.1073/pnas.1906513116
出版社：The National Academy of Sciences of the United States of America
摘要：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 La 1/3 Sr 2/3 FeO 3 (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/ c m 2 , a significant value arising from electron transfer between F e O 6 octahedra. Our calculations reveal that artificial structuring of LSFO and other mixed valence oxides with robust charge ordering in the solid solution phase can lead to charge-order–induced ferroelectricity..
关键词：ferroelectricity ; density;functional theory ; perovskite;oxide superlattices ; charge ordering
