Broken time-reversal symmetry in a Josephson junction with an Anderson impurity between a two-band and a single-band superconductor

A Josephson junction consisting of an Anderson impurity weakly coupled on one side with a two-band superconductor and on the other side with a a single-band superconductor exposes a time-reversal breaking ground state within a finite domain of the U-J plane (here U is the correlation strength and J is the coupling between the two bands). In this regime, the impurity magnetic moment is attenuated and order-parameter phase differences across the junction are neither 0 nor π. This indicates a fundamental and distinct role of strong correlations: driving a system into a time-reversal breaking ground state.