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

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), A(n+...

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Detalles Bibliográficos
Autores principales: Stone, Greg, Ophus, Colin, Birol, Turan, Ciston, Jim, Lee, Che-Hui, Wang, Ke, Fennie, Craig J., Schlom, Darrell G., Alem, Nasim, Gopalan, Venkatraman
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5013660/
https://www.ncbi.nlm.nih.gov/pubmed/27578622
http://dx.doi.org/10.1038/ncomms12572
Descripción
Sumario: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), A(n+1)B(n)O(3n+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 Sr(n+1)Ti(n)O(3n+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.