Gap States in Dilute Magnetic Alloy Superconductors

Abstract

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 $T_{0} \alt T_{c0}$ and $T_{0} \agt T_{c0}$ ($T_0$: 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.

4 pages in ReVTeX including 4 encapsulated Postscript figures