Engineered Josephson diode effect in kinked Rashba nanochannels

TL;DR

This paper demonstrates how geometric design and magnetic fields in Rashba nanostrips can control the superconducting diode effect and induce topological states, advancing superconducting device engineering.

Contribution

It introduces a method to control the Josephson diode effect through geometry and magnetic fields in Rashba nanostrips, linking it to topological phases and Majorana states.

Findings

Phase diagram showing geometry and field dependence of the diode effect

Identification of trivial zero-energy Andreev bound states

Potential for designing topologically protected superconducting devices

Abstract

The superconducting diode effect, reminiscent of the unidirectional charge transport in semiconductor diodes, is characterized by a nonreciprocal, dissipationless flow of Cooper pairs. This remarkable phenomenon arises from the interplay between symmetry constraints and the inherent quantum behavior of superconductors. Here, we explore the geometric control of the diode effect in a kinked nanostrip Josephson junction based on a two-dimensional electron gas (2DEGs) with Rashba spin-orbit interaction. We provide a comprehensive analysis of the diode effect as a function of the kink angle and the out-of-plane magnetic field. Our analysis reveals a rich phase diagram, showcasing a geometry and field-controlled diode effect. The phase diagram also reveals the presence of an anomalous Josephson effect related to the emergence of trivial zero-energy Andreev bound states, which can evolve into Majorana bound states. Our findings indicate that the exceptional synergy between geometric control of the diode effect and topological phases can be effectively leveraged to design and optimize superconducting devices with tailored transport properties.