Andreev tunneling through an interacting quantum dot: Numerical renormalization group approach

摘要

We theoretically study the Andreev tunneling through a quantum dot (QD) coupled to normal and superconducting leads by means of the numerical renormalization group (NRG) method. As the coupling between the QD and the normal lead gets smaller, we find that the peak structure is developed in the conductance, which clearly features crossover behavior between two distinct regions of spin-singlet ground states, i.e. the superconducting singlet state and the Kondo singlet state. We discuss the characteristic transport properties of the Andreev tunneling in the light of local electron correlations in the QD.