We demonstrate that ultraviolet Raman spectroscopy is an effective technique to measure the transition temperature, Tc, 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. Tc 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.
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
Tenne, Dmitri; Bruchhausen, A.; Lanzillotti-Kimura, N. D.; Fainstein, A.; Katiyar, R. S.; Cantarero, A.; and Soukiassian, A.. (2006). "Probing Nanoscale Ferroelectricity by Ultraviolet Raman Spectroscopy". Science, 313(5793), 1614-1616. http://dx.doi.org/10.1126/science.1130306