Tuning the 0-π Josephson junction with a magnetic impurity: Role of tunnel contacts, exchange coupling, e-e interactions and high-spin states

We propose Josephson junction with a high-spin magnetic impurity sandwiched between two superconductors. This system shows a $\pi$ junction behavior as a function of the spin magnetic moment state of the impurity, the interface transparency, exchange coupling and electron-electron interactions in the system. The system is theoretically analyzed for possible reason behind the $\pi$ shift. The crucial role of spin flip scattering is highlighted. Possible applications in quantum computation of our proposed tunable high spin magnetic impurity $\pi$ junction is underscored.