Yu-Shiba-Rusinov bound states boost odd-frequency superconductivity

TL;DR

This paper predicts that zero energy Yu-Shiba-Rusinov bound states in specific junctions significantly enhance surface odd-frequency superconductivity, with implications for superconducting spintronics and detection methods.

Contribution

It introduces the novel idea that YSR bound states can induce a multi-fold increase in odd-frequency superconductivity in certain junctions, linking bound states to superconducting symmetry.

Findings

Zero energy YSR states cause a 0- transition in Josephson junctions.

YSR states lead to dominance of odd-frequency, equal spin-triplet pairing.

Absence of YSR states results in even-frequency superconductivity dominance.

Abstract

We predict that the occurence of zero energy Yu-Shiba-Rusinov(YSR) bound states in two different setups, metal-spin flipper-metal-s-wave superconductor ($N_{1}-sf-N_{2}-S$) and superconductor-metal-spin flipper-metal-superconductor ($S-N_{1}-sf-N_{2}-S$) junctions, can generate multi-fold enhancement of surface-induced odd-frequency superconductivity. On the other hand, in the absence of these bound states, even-frequency superconductivity dominates. Specifically, in a $S-N_{1}-sf-N_{2}-S$ Josephson junction, the emergence of zero energy YSR bound states leads to a $0-\pi$ junction transition and surface odd-frequency superconductivity dominance. Notably, odd-frequency superconductivity vanishes in the absence of YSR-bound states. Interestingly, the equal spin-triplet pairing is the dominant component in the surface induced odd-frequency superconductivity in both setups, which could have important implications for superconducting spintronics. Overall, our findings may help to detect the presence of YSR-bound states through the observation of surface induced odd-frequency superconductivity and contribute to a better understanding of their relationship.