Stability of supercurrents and condensates in type I superconductors
Abstract
Excitations of Cooper pairs into noncondensed bound pairs are similar to excitations of true bosons out of the BoseEinstein condensate. Using the Landau criterion of superfluidity we evaluate the critical current above which these pairexcitations would lead to a finite resistivity. The predicted value strongly depends on the chosen approximation. The Thouless approach based on the Galitskii Tmatrix and the KadanoffMartin theory which is in many aspects equivalent to the BCS theory, both lead to zero critical velocity, what is in conflict with the mere existence of supercurrents. In contrast, the Tmatrix with multiple scattering corrections provides the critical velocity of pair excitation which is √3times larger than the critical velocity of pair breaking. This agrees with the experimentally well established fact that supercurrents in type I superconductors are limited by pair breaking, not by pair excitation.
 Publication:

European Physical Journal B
 Pub Date:
 January 2014
 DOI:
 10.1140/epjb/e2013409322
 arXiv:
 arXiv:1008.5293
 Bibcode:
 2014EPJB...87....8L
 Keywords:

 Solid State and Materials;
 Condensed Matter  Superconductivity
 EPrint:
 doi:10.1140/epjb/e2013409322