Evaluation of High-Frequency Ultrasonic Attenuation in Superconductors in the Bardeen-Cooper-Schrieffer Theory of Superconductivity

Abstract

Calculations are given of the ratio of the attenuations of longitudinal sound waves in the superconducting and normal states according to the BCS theory of superconductivity for an isotropic model at arbitrary frequencies and temperatures. It is predicted that there is a discontinuity in attenuation at a frequency corresponding to the energy gap.