Nonequilibrium Quasiparticle Distribution Induced by Kondo Defects

It is shown that in resistive nanowires out of equilibrium containing either single- or two-channel Kondo impurities the distribution function f(E,U) obeys scaling behavior in terms of the quasiparticle energy E and the bias voltage U. The numerically calculated f(E,U) curves explain quantitatively recent experiments on Cu and Au nanowires. The systematics of the impurity concentration c(imp) extracted from the comparison between theory and results on various Cu and Au samples strongly suggests that in these systems the scaling arises from magnetic Kondo impurities.