BRILLOUIN LIGHT-SCATTERING INVESTIGATION OF ELASTIC ANOMALY FROM SUPERLATTICES

In this paper we report some new experimental results concerning the e lastic properties of periodic and quasiperiodic superlattices studied by means of Brillouin spectroscopy. The observation of both bulk and s urface acoustic phonons as well as the fitting using effective medium approximation on the phonon spectrum enables us to extract accurately some relevant effective elastic constants in both structures. We have verified that the elastic anomaly which occurs in the periodic structu res is also present in quasiperiodic ones. These results imply that th e interaction mechanism of Fermi electrons with reduced Brillouin zone boundary is not responsible for the observed elastic anomalies. The c omparative study of these superlattices proves that the elastic anomal y is relevant directly to interfacial effects.