π junction behavior and Andreev bound states in Kondo quantum dots with superconducting leads -: art. no. 174502

We investigate the temperature- and coupling-dependent transport through Kondo dot contacts with symmetric superconducting s-wave leads. For finite temperature T we use a superconducting extension of a self-consistent auxiliary boson scheme (SNCA), while at T=0 a perturbative renormalization group treatment is applied. The finite-temperature phase diagram for the 0-pi transition of the Josephson current in the junction is established and related to the phase-dependent position of the subgap Kondo resonance with respect to the Fermi energy. The conductance of the contact is evaluated in the zero-bias limit. It approaches zero in the low-temperature regime, however, at finite T its characteristics are changed through the coupling- and temperature-dependent 0-pi transition.