Atomic scale imaging of competing polar states in a Ruddlesden-Popper layered oxide

Greg Stone, Colin Ophus, Turan Birol, Jim Ciston, Che Hui Lee, Ke Wang, Craig J. Fennie, Darrell G. Schlom, Nasim Alem, Venkatraman Gopalan

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31 Scopus citations

Abstract

Layered complex oxides offer an unusually rich materials platform for emergent phenomena through many built-in design knobs such as varied topologies, chemical ordering schemes and geometric tuning of the structure. A multitude of polar phases are predicted to compete in Ruddlesden-Popper (RP), An+1BnO3n+1, thin films by tuning layer dimension (n) and strain; however, direct atomic-scale evidence for such competing states is currently absent. Using aberration-corrected scanning transmission electron microscopy with sub-Ångstrom resolution in Srn+1TinO3n+1 thin films, we demonstrate the coexistence of antiferroelectric, ferroelectric and new ordered and low-symmetry phases. We also directly image the atomic rumpling of the rock salt layer, a critical feature in RP structures that is responsible for the competing phases; exceptional quantitative agreement between electron microscopy and density functional theory is demonstrated. The study shows that layered topologies can enable multifunctionality through highly competitive phases exhibiting diverse phenomena in a single structure.

Original languageEnglish (US)
Article number12572
JournalNature communications
Volume7
DOIs
StatePublished - Aug 31 2016

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© 2016 The Author(s).

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