Nonequilibrium conductance of asymmetric nanodevices in the Kondo regime

The scaling properties of the conductance of a Kondo impurity connected to two leads that are in or out of equilibrium has been extensively studied, both experimentally and theoretically. From these studies, a consensus has emerged regarding the analytic expression of the scaling function. The question addressed in this Brief Report concerns the properties of the experimentally measurable coefficient α present in the term describing the leading dependence of the conductance on eV/ TK, where V is the source-drain voltage and TK is the Kondo temperature. We study the dependence of α on the ratio of the lead-dot couplings for the particle-hole symmetric Anderson model and find that this dependence disappears in the strong-coupling Kondo regime in which the charge fluctuations of the impurity vanish.