Acoustic properties of nanoscale oxide heterostructures probed by UV Raman spectroscopy

We study high quality molecular-beam epitaxy grown BaTiO3/SrTiO3 superlattices using ultraviolet Raman spectroscopy. In the low energy spectral region, acoustic phonon doublets are observed. These axe due to the artificial superlattice periodicity and consequent folding of the acoustic phonon dispersion. From the study of samples with different BaTiO3/SrTiO3 layer thicknesses the effective sound velocities within each of the layers are obtained.