Pressure Dependence of Acoustic-Mode-Soft-Optic-Mode Interactions in Ferroelectric BaTiO3

Abstract
Measurements of the pressure dependence of the Raman and Brillouin spectra of tetragonal BaTiO3 at 296 K have shown that the frequency separation between the two branches of the coupled acoustic-mode-soft-optic-mode system increases and the mode coupling decreases with increasing pressure. The results yield independent quantitative support for the model recently discussed by Fleury and Lazay and demonstrate the utility of pressure studies as a unique means of investigating coupled-mode interactions.