Gap states in dilute magnetic alloy superconductors

We study states in the superconducting gap induced by magnetic impurities using self-consistent quantum Monte Carlo with maximum entropy and formally exact analytic continuation methods. The magnetic impurity susceptibility has different characteristics for T-0 less than or similar to T-c0 and T-0 greater than or similar to T-c0 (T-0: Kondo temperature; T-c0: superconducting transition temperature) due to the crossover between a doublet and a singlet ground state. We systematically study the location and the weight of the gap states and the gap parameter as a function of T-0/T-c0 and the concentration of the impurities.