Probing Nanoscale Ferroelectricity by Ultraviolet Raman Spectroscopy

Dmitri Tenne, Boise State University
A. Bruchhausen, Centro Atomico Bariloche & Instituto Balseiro
N. D. Lanzillotti-Kimura, Centro Atomico Bariloche & Instituto Balseiro
A. Fainstein, Centro Atomico Bariloche & Instituto Balseiro
R. S. Katiyar, University of Puerto Rico
A. Cantarero, University of Valencia
A. Soukiassian, Pennsylvania State University

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This is an author-produced, peer-reviewed version of this article. The final, definitive version of this document can be found online at Science, published by American Association for the Advancement of Science. Copyright restrictions may apply. doi: 10.1126/science.1130306

Abstract

We demonstrate that ultraviolet Raman spectroscopy is an effective technique to measure the transition temperature, T_c, accurately in ferroelectric ultrathin films and superlattices. We show that one-unit-cell thick BaTiO₃ layers in BaTiO₃/SrTiO₃ superlattices are not only ferroelectric (Tc as high as 250 K), but also polarize the quantum paraelectric SrTiO₃ layers adjacent to them. T_c was tuned by ~ 500 K by varying the thicknesses of BaTiO₃ and SrTiO₃ layers, revealing the essential roles of electrical and mechanical boundary conditions for nanoscale ferroelectricity.