Cubic spin-orbit coupling and anomalous Josephson effect in planar junctions

TL;DR

This paper explores the effects of cubic spin-orbit coupling in two-dimensional Josephson junctions, revealing unique current-phase relations, tunable supercurrents, and implications for superconducting spintronics and Majorana states.

Contribution

It introduces the study of cubic spin-orbit coupling in Josephson junctions, showing how it leads to anharmonic current-phase relations and tunable supercurrents, which were not previously explored.

Findings

Anharmonic current-phase relation in cSOC junctions

Tunable anomalous phase shift and supercurrent

Presence of f-wave spin-triplet correlations

Abstract

Spin-orbit coupling in two-dimensional systems is usually characterized by Rashba and Dresselhaus spin-orbit coupling (SOC) linear in the wave vector. However, there is a growing class of materials which instead support dominant SOC cubic in the wave vector (cSOC), while their superconducting properties remain unexplored. By focusing on Josephson junctions in Zeeman field with superconductors separated by a normal cSOC region, we reveal a strongly anharmonic current-phase relation and complex spin structure. An experimental cSOC tunability enables both tunable anomalous phase shift and supercurrent, which flows even at the zero-phase difference in the junction. A fingerprint of cSOC in Josephson junctions is the f-wave spin-triplet superconducting correlations, important for superconducting spintronics and supporting Majorana bound states.