CONTRIBUTION OF ELECTRONIC-STRUCTURE TO ELASTIC ANOMALIES IN METALLIC SUPERLATTICES

One candidate for the origin of the elastic anomaly reported for metallic superlattices is electronic effects resulting from the interaction of the Fermi surface and the new Brillouin-zone boundary introduced by modulation. We have used a simple model to study the singularities in the total energy which are due to contact of the Fermi surface with the zone boundary, and applied our results to the elastic properties. Although we find that the electronic effects do indeed lead to singularities in the variation of elastic constants with modulation wavelength, these are found to be weak and we expect them normally to make no significant contributions to elastic properties of real systems.