Superconducting Diode Effect in Two-dimensional Topological Insulator Edges and Josephson Junctions

TL;DR

This paper investigates the superconducting diode effect in two-dimensional topological insulator edges and Josephson junctions, demonstrating how Zeeman fields induce non-reciprocal critical currents with potential for superconducting electronics.

Contribution

It reveals the mechanism of non-reciprocal critical currents in 2D TIs under Zeeman fields and quantifies diode efficiency in different geometries, advancing understanding of superconducting diode effects.

Findings

Maximum diode efficiency of 1 in uniform 2D TI

Diode efficiency of approximately 0.17 in long Josephson junctions

Zeeman fields induce circulating edge currents enabling non-reciprocity

Abstract

The superconducting diode effect -- the dependence of critical current on its direction -- can arise from the simultaneous breaking of inversion and time-reversal symmetry in a superconductor and has gained interest for its potential applications in superconducting electronics. In this letter, we study the effect in a two-dimensional topological insulator (2D TI) in both a uniform geometry as well as in a long Josephson junction. We show that in the presence of Zeeman fields, a circulating edge current enables a large non-reciprocity of the critical current. We find a maximum diode efficiency 1 for the uniform 2D TI and $(\sqrt{2} - 1)^2 \approx 0.17$ for the long Josephson junction.