A Josephson diode passes current with zero resistance in one direction but is resistive in the other direction. While such an effect has been observed in several platforms, a large and tunable Josephson diode effect has been rare. Here we report that a simple device consisting of a topological-insulator (TI) nanowire side-contacted by superconductors to form a lateral Josephson junction presents a large diode effect with the efficiency η reaching 0.3 when a parallel magnetic field B∣∣ is applied. Interestingly, the sign and the magnitude of η is tunable not only by B∣∣ but also by the back-gate voltage. This diode effect can be understood by modeling the system as a nano-SQUID, in which the top and bottom surfaces of the TI nanowire each form a line junction and B∣∣ creates a magnetic flux to thread the SQUID loop. This model further shows that the observed diode effect marks the emergence of topological superconductivity in TI-nanowire-based Josephson junction.
@article{arxiv.2412.16569,
title = {Tunable superconducting diode effect in a topological nano-SQUID},
author = {Ella Nikodem and Jakob Schluck and Max Geier and Michal Papaj and Henry F. Legg and Junya Feng and Mahasweta Bagchi and Liang Fu and Yoichi Ando},
journal= {arXiv preprint arXiv:2412.16569},
year = {2025}
}
Comments
Final version, 34 pages total; 21 pages of main text with 5 figures, 13 pages of supplement with 8 figures. The raw data and codes are available at the online depository Zenodo with the identifier https://doi.org/10.5281/zenodo.14576331