Strong anomalous proximity effect from spin-singlet superconductors

TL;DR

This paper proposes a new method to observe the anomalous proximity effect, typically associated with spin-triplet superconductors, using a hybrid device of a semiconductor and high-$T_c$ cuprate superconductor with spin-orbit coupling.

Contribution

It demonstrates that the anomalous proximity effect can occur in a spin-singlet superconductor hybrid, providing an alternative route to study topologically protected quasiparticles.

Findings

Anomalous proximity effect can be realized in semiconductor/high-$T_c$ cuprate superconductor hybrids.

The effect is linked to coexistence of $d$-wave pairing and spin-orbit coupling.

This approach offers a new way to explore topological superconductivity phenomena.

Abstract

The proximity effect from a spin-triplet $p_x$-wave superconductor to a dirty normal-metal has been shown to result in various unusual electromagnetic properties, reflecting a cooperative relation between topologically protected zero-energy quasiparticles and odd-frequency Cooper pairs. However, because of a lack of candidate materials for spin-triplet $p_x$-wave superconductors, observing this effect has been difficult. In this paper, we demonstrate that the anomalous proximity effect, which is essentially equivalent to that of a spin-triplet $p_x$-wave superconductor, can occur in a semiconductor/high-$T_c$ cuprate superconductor hybrid device in which two potentials coexist: a spin-singlet $d$-wave pair potential and a spin--orbit coupling potential sustaining the persistent spin-helix state. As a result, we propose an alternative and promising route to observe the anomalous proximity effect related to the profound nature of topologically protected quasiparticles and odd-frequency Cooper pairs.