Ferroelectricity-Induced Coupling between Light and Terahertz-Frequency Acoustic Phonons in BaTiO3/SrTiO3 Superlattices

A. BRUCHHAUSEN; A. FAINSTEIN; A. SOUKIASSIAN; D. G. SCHLOM; X. X. XI; M. BERNHAGEN; P. REICHE; R. UECKER

PHYSICAL REVIEW LETTERS

AMER PHYSICAL SOC

Año: 2008 vol. 101 p. 197402 - 197402

0031-9007

We report a UV-Raman study of folded acoustic vibrations in epitaxial ferroelectric BaTiO3/SrTiO3 superlattices. The folded acoustic doublets show an anomalous temperature dependence disappearing above the ferroelectric transition, which is tuned by varying the thickness of the BaTiO3 and SrTiO3 layers. A mechanism involving the acoustic phonon modulation of the spatially periodic ferroelectric polarization explains the observed temperature dependence. These results demonstrate the strong coupling between sound, charge, and light in these multifunctional nanoscale ferroelectrics.