Josephson Effect through a Magnetic Metallofullerene Molecule
Résumé
We investigate the Josephson effect through a molecular quantum dot magnet connected to superconducting leads. The molecule depicts a metallofullerene where the spin of the magnetic atom inside the carbon shell is assumed to be isotropic. It is coupled to the electron spin on the dot via exchange coupling. Using the numerical normalization group method we calculate the Andreev levels and the supercurrent and examine intertwined effect of the exchange coupling, Kondo correlation, and superconductivity on the current. Exchange coupling typically suppresses the Kondo correlation so that the system undergoes a phase transition from 0 to $\pi$ state as |J| increases, where J is the exchange coupling constant. Antiferromagnetic coupling is found to drive exotic transitions: the reentrance to the Pi state for a small superconducting gap and the restoration of 0 state for large J. We suggest that the asymmetric dependence of supercurrent on J could be used as to detect the sign of J in experiments.
Origine : Fichiers produits par l'(les) auteur(s)