Abstract:

The propagation of elastic waves in macroscopically periodic composites consisting of core-shell spherical scatterers in a homogeneous host medium is studied by means of numerical calculations using the layer-multiple-scattering method. By an appropriate choice of the constituent materials, these crystals exhibit wide absolute frequency gaps, over which no elastic wave can propagate in the composite medium, whatever the direction of its propagation. We analyze the detailed structure of transmission spectra of finite slabs of such crystals in conjunction with the corresponding complex-band-structure and density-of-states diagrams, and emphasize aspects of the underlying physics which have not been discussed previously.