Electromagnetic penetration depth in superconductors with magnetic impurities

Abstract

The electromagnetic penetration depth $\lambda$ in the local limit is calculated for superconductors containing magnetic impurities and having local excited states within the energy gap according to Shiba's theory. The penetration depth is presented as a function of the normal-state conductivity ${\sigma }_n$, the temperature $T$, the transition temperature $T_c$ of the alloy and that $T_{c0\mathrm{}}$ of the pure host metal, and Shiba's parameter ${\epsilon }_0$ (the normalized position in the energy gap of the excited state associated with a single magnetic-impurity atom).