Effect of Magnetic Impurity Correlations on Josephson Tunneling

TL;DR

This paper investigates how magnetic impurity correlations at low temperatures can restore superconducting properties and affect Josephson tunneling, deviating from traditional models, with applications to both low- and high-temperature superconductors.

Contribution

It introduces a theoretical framework for impurity correlation effects on Josephson tunneling, extending understanding beyond classical models and applying to experimental data.

Findings

Magnetic impurity correlations cause a 'recovery' of superconducting properties.

Deviation of Josephson current from classical models observed.

Prediction of similar effects in high-temperature superconductors.

Abstract

The ordering trend of magnetic impurities at low temperature results in the frustration of the pair-breaking effect and induces a ``recovery'' of superconducting properties. We show that this effect manifests itself in the deviation of the Josephson current amplitude from the values obtained within the Ambegaokar-Baratoff and the Abrikosov-Gor'kov models. We consider both weak and strong-coupling cases. The theory is applied to describe the experimental data obtained for the low-$T_c$ superconductor SmRh$_4$B$_4$. We further predict a ``recovery'' effect of the Josephson current in high-temperature superconductors.