Anomalous Behavior of Surface Acoustic Waves in Cu/Nb Superlattices

Abstract

Brillouin-scattering measurements show an anomalous dip in the elastic constants of Nb/Cu superlattices for superlattice wavelengths of \ensuremath{\lesssim} 100 \AA{}. This dip is correlated with changes in the electrical resistivity of the samples giving the first evidence that electronic effects are responsible for phonon softening in these materials.