Elastic point contact spectroscopy of electron-phonon interaction in superconductive lead

Abstract

A method for experimental determination of the spectral function of electron-phonon interaction (SF EPI) in superconductors with strong coupling has been developed. The method is based on analysis of non-linear current-voltage characteristics of point heterocontacts superconductor-normal metal. The nonlinearities arise in the elastic component of the current through the hetero-contact due to dependence on energy of the complex function of the energy gap in superconductor, and they have a similar nature as ones observed in superconducting tunnel contacts. For the purpose of present study the lead as a typical superconductor with strong EPI was chosen. In order to obtain the SE EPI the Eliashberg equation was solved numerically following the McMillan-Rowell method. Our solution is in good agreement with the results of elastic tunnel spectroscopy of superconductors as well as with the data provided by the inelastic point contact spectroscopy in the normal state.