Theory of Josephson effect in strongly correlated electron systems

We study Josephson effect in superconducting junction based on the repulsive Hubbard model on the square lattice with the fluctuation exchange approximation and the recursive Green's function method. It is shown that the proximity effect is suppressed by the repulsive interaction in the normal metal, and consequently Josephson current in superconductor/normal metal/superconductor junction is reduced due to the strong correlation effect. This is because the imaginary part of the self energy, which facilitates the damping effect, grows with the repulsive interaction.