Theory of proximity effect in two-dimensional unconventional superconductor with Rashba spin-orbit interaction

TL;DR

This paper investigates how Rashba spin-orbit coupling influences the proximity effect in two-dimensional unconventional superconductor junctions, revealing that RSOC can suppress or enhance the effect depending on the pairing symmetry.

Contribution

It demonstrates the impact of Rashba spin-orbit coupling on the anomalous proximity effect in 2D unconventional superconductor junctions, highlighting the switchable nature of the effect.

Findings

Proximity effect disappears with increasing RSOC in spin-triplet p-wave junctions.

Proximity effect is enhanced and switchable in d_{xy}-wave superconductor junctions with large RSOC.

Zero-energy LDOS and odd-frequency pair amplitude increase with RSOC strength.

Abstract

We study the anomalous proximity effect in diffusive normal metal (DN)/unconventional superconductor junctions, where the local density of states (LDOS) in the DN has a zero-energy peak due to the penetration of the odd-frequency spin-triplet $s$-wave pairing. In this study, we consider a two-dimensional unconventional superconductor on the substrate in the presence of a Rashba spin-orbit coupling (RSOC) $\lambda$, where the Rashba vector is parallel to the $z$-direction. The anomalous proximity effect, originally predicted in spin-triplet $p$-wave superconductor junctions, is sensitive to the RSOC. It disappears with the increase of $\lambda$. On the other hand, the anomalous proximity effect can be switched on by the large $\lambda$ values in the spin-singlet $d_{xy}$-wave superconductor junctions. The resulting zero-energy LDOS and the magnitude of the odd-frequency spin-triplet $s$-wave pair amplitude increase with the increase of $\lambda$.