Kondo Screening Cloud and the Charge Staircase in One-Dimensional Mesoscopic Devices

Abstract

We propose that the finite size of the Kondo screening cloud, ξK , can be probed by measuring the charge quantization in a one-dimensional system coupled to a small quantum dot. When the chemical potential μ in the system is varied at zero temperature, one should observe charge steps whose locations are at values of μ that are controlled by the Kondo effect when the system size L is comparable to ξK . We show that, if the standard Kondo model is used, the ratio between the widths of the Coulomb blockade valleys with odd or even number of electrons is a universal scaling function of ξK/L . If we take into account electron-electron interactions in a single-channel wire, this ratio also depends on the parameters of the effective Luttinger model; in addition, the scaling is weakly violated by a marginal bulk interaction. For the geometry of a quantum dot embedded in a ring, we show that the dependence of the charge steps on a magnetic flux through the ring is controlled by the size of the Kondo screening cloud.