Ultrasonic attenuation in superconductors: theory of the effect of scattering of electrons by thermal phonons

摘要: A Debye phonon spectrum and a spherical Fermi surface are assumed for the purpose of explicit calculation, but effects described expected to occur in all pure superconductors with high enough Tc. Both at small ql (q is sound wavevector l electron mean free path), over range greater than unity, thermal phonons have marked effect on relaxation electrons superconducting state, not normal state. Thus BCS relationship ultrasonic attenuation ratio between states, which applicable when impurity scattering dominant, no longer applies by becomes important.