EFFECT OF MAGNETIC IMPURITY CORRELATIONS ON JOSEPHSON TUNNELING

The ordering trend of magnetic impurities at low temperature results i n the frustration of the pair-breaking effect and induces a 'recovery' of superconducting properties. We show that this effect manifests its elf in the deviation of the Josephson current amplitude from the value s obtained within the Ambegaokar-Baratoff and the Abrikosov-Gor'kov mo dels. We consider both weak and strong-coupling cases. The theory is a pplied to describe the experimental data obtained for the low-T-c supe rconductor SmRh4B4. We further predict a 'recovery' effect of the Jose phson current in high-temperature superconductors. (C) 1998 Elsevier S cience B.V.