Topological pi Josephson junction in superconducting Rashba wires

TL;DR

This paper investigates topological phases in Rashba nanowires with sign-changing spin-orbit coupling, revealing a topological -junction with unique supercurrent properties that are robust against disorder.

Contribution

It introduces a new topological -junction in Rashba nanowires with sign-changing spin-orbit coupling, highlighting its robustness and distinctive supercurrent behavior.

Findings

Supports three topological phases protected by chiral symmetry

Displays a -junction with maximum supercurrent near zero phase difference

Features are robust against disorder and magnetic fields violating chiral symmetry

Abstract

In this work we show that Rashba-based topological superconductor nanowires, where the spin-orbit coupling may change its sign, support three topological phases protected by chiral symmetry. When a superconducting phase gradient is applied over the interface of the two nontrivial phases, the Andreev spectrum is qualitatively phase shifted by \pi compared to usual Majorana weak links. The topological \pi-junction has the striking property of exhibiting maximum supercurrent in the vicinity of vanishing phase difference. Qualitative features of the junction are robust against disorder and magnetic fields violating chiral symmetry. The studied system could be realized by local gating of the wire or by an appropriate stacking of permanent magnets in synthetic Rashba systems.