Results on nonequilibrium thin-film superconductors using the kinetic equation approach

An attempt is made to find the density instability to a superconducting multigap state by using the kinetic equations. This approach is general enough to include both the possibility of anomalous diffusion and the purely kinetic instability proposed by Iguchi and Konno. No instability to small density fluctuations is found. The possibility of an instability involving a nucleation step cannot be ruled out, however. Results for the solutions of the distribution functions in the homogeneous case are also presented, illustrating the jump to the normal state, the extent to which the excited quasiparticles can be described by a few thermodynamic parameters, and the dependence upon the phonon escape time