Collective Excitations in Strong-Coupling Superconducting Alloys

Abstract

The mean-free-path dependence of collective excitations in strong-coupling superconducting alloys is investigated by extension of the Fermi-liquid theory, which was developed by Larkin and Migdal for pure strong-coupling superconductors. Numerical results, which are presented, show that the dependence of the energy of transverse collective excitations on mean free path is large enough to suggest that the precursor in the infrared absorption spectrum of lead alloys is not due to collective excitations.