NUMERICAL STUDY ON JOSEPHSON-CURRENT FLUCTUATIONS IN A DIRTY SNS JUNCTION - THE EFFECT OF INCOMPLETE ANDREEV REFLECTION

Mesoscopic fluctuations of the DC Josephson current in a dirty SNS jun ction (S: superconductor, N: normal conductor) are studied numerically in the presence of barrier potentials at the NS interfaces, which red uce the Andreev reflection probability. The results show that the crit ical-current fluctuations in the long-junction limit are suppressed as the Andreev reflection probability decreases while those in the short -junction limit are relatively insensitive to reductions in the Andree v reflection probability. Therefore, the effect of incomplete Andreev reflection is significant in the long-junction limit. We show that the quantitative difference between our previous theory and the experimen tal results of Takayanagi et al. is well explained by taking the effec t of incomplete Andreev reflection into account.