Eliashberg theory applied to the study of an NbGe series
Abstract
We use the strong coupling theory of superconductivity to perform a detailed analysis of the Eliashberg functions alpha(exp 2)F(omega), for thirteen samples of NbGe with critical temperatures ranging from 7.0 to 21.1 K. As critical temperature increases, we analyze the general trends of the electronphonon coupling parameter lambda, of the integral of alpha(exp 2)F(omega)'A', and of other characteristics of alpha(exp 2)F(omega) on the basis of empirical criteria. While we find that the samples have in general the behavior expected, a closer analysis points to an overall attenuation in alpha(exp 2)F(omega) of unclear origin. Though the gap edge, (delta)0, appears to be well described by the (alpha)(exp 2)F(omega) obtained, the thermodynamic critical field agrees poorly with that reproduced by alpha(exp 2)F(omega) in the only case where the necessary (tunneling alpha(sup 2)F(omega) critical field measurements) data are available. Our analysis suggests there is a gross uncertainty in the measured H(sub c)(0). The overall analysis shows that the samples obtained are of enough quality to already give meaningful results upon inversion of the tunneling data.
 Publication:

Unknown
 Pub Date:
 July 1991
 Bibcode:
 1991etas.rept.....B
 Keywords:

 Coupling;
 Critical Temperature;
 Electron Phonon Interactions;
 Electron Tunneling;
 High Temperature Superconductors;
 Superconductivity;
 Transition Temperature;
 Germanium;
 Josephson Junctions;
 Niobium;
 SolidState Physics