Gap States in Dilute Magnetic Alloy Superconductors

TL;DR

This paper investigates how magnetic impurities create states within the superconducting gap, analyzing their properties across different impurity concentrations and temperature regimes using advanced computational methods.

Contribution

It provides a systematic analysis of impurity-induced gap states in superconductors, highlighting the crossover behavior related to the Kondo temperature and superconducting transition temperature.

Findings

Gap states' location and weight depend on impurity concentration and temperature.

Magnetic impurity susceptibility varies across the crossover between doublet and singlet ground states.

The study offers insights into the interplay between magnetic impurities and superconductivity.

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.