Phonon spectroscopy

Abstract

Rapid progress has been taken place in phonon spectroscopy since the review by Bron in 1980. The authors restrict themselves to acoustic branch phonons, and describe the improvements in technique that make it now possible to study phonons in some materials right up to the Brillouin zone edge. Major advances have taken place particularly in the areas of phonon imaging and in the use of superconducting tunnel junctions. It is observed that the transport of high-frequency phonons is influenced strongly by focusing effects due to crystal anisotropy. In the context of the electron-phonon interaction, the authors describe the scattering and emission of phonons by bound and free electrons. Another area of great interest relates to the scattering of phonons at boundaries and interfaces, and their connection with disordered systems and other structural defects.