We investigate the supercurrent through a quantum dot for the whole range of couplings using the numerical renormalization group method. We find that the Josephson current switches abruptly from a π- to a 0-phase as the coupling increases. At intermediate couplings the total spin in the ground state depends on the phase difference between the two superconductors. Our numerical results can explain the crossover in the conductance observed experimentally by Buitelaar \textit{et al.} [Phys. Rev. Lett. \textbf{89}, 256 801 (2002)].
@article{arxiv.cond-mat/0312271,
title = {Kondo Effect and Josephson Current through a Quantum Dot between Two Superconductors},
author = {Mahn-Soo Choi and Minchul Lee and Kicheon Kang and W. Belzig},
journal= {arXiv preprint arXiv:cond-mat/0312271},
year = {2009}
}
Comments
Fig.2 and corresponding text have been changed; Several other small changes