Tunneling spectroscopy of topological insulator Josephson junctions
4 affiliations
- 1Physics Institute II, University of Cologne, Zülpicher Str. 77, 50937 Köln, Germany.
- 2Institute for Quantum Information, RWTH Aachen University, 52056 Aachen, Germany.
- 3Max Planck Institute for the Science of Light, 91058 Erlangen, Germany.
- 4Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
Abstract
In the seminal proposal by Fu and Kane, the superconducting proximity effect is used to realize topological superconductivity in the topological surface state (TSS) of a 3D topological insulator (TI). In a Josephson junction made on the TI surface, the spin-momentum locking of the TSS guarantees the existence of spin nondegenerate, perfectly transmitted Andreev modes. These modes lead to gap closing as a function of the superconducting phase difference φ. Here, we report the observation of highly transmissive Andreev modes in a TI Josephson junction, probed via tunnel contacts and φ controlled by a flux loop. Within our experimental resolution, they could indicate a gap closing and reopening. This phenomenon is observed for a wide range of chemical potentials, supporting its TSS origin. Under an applied magnetic field, highly transmissive modes are observed locally, matching theoretical predictions for Josephson vortices in the TSS. Our results support the fundamental role of spin-momentum locking in the Andreev physics in the TSS.
Related
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BibTeX
@article{schluck2026tunneling,
title = {{Tunneling spectroscopy of topological insulator Josephson junctions}},
author = {Jakob Schluck and Ella Nikodem and Anton Montag and Alexander Ziesen and Mahasweta Bagchi and Fabian Hassler and Yoichi Ando},
journal = {Science Advances},
year = {2026},
month = oct,
doi = {10.1126/sciadv.aeg0687},
url = {https://www.science.org/doi/abs/10.1126/sciadv.aeg0687},
note = {CC BY},
}
RIS
TY - JOUR
TI - Tunneling spectroscopy of topological insulator Josephson junctions
AU - Jakob Schluck
AU - Ella Nikodem
AU - Anton Montag
AU - Alexander Ziesen
AU - Mahasweta Bagchi
AU - Fabian Hassler
AU - Yoichi Ando
PY - 2026
DA - 2026/10/30
JO - Science Advances
DO - 10.1126/sciadv.aeg0687
UR - https://www.science.org/doi/abs/10.1126/sciadv.aeg0687
AB - In the seminal proposal by Fu and Kane, the superconducting proximity effect is used to realize topological superconductivity in the topological surface state (TSS) of a 3D topological insulator (TI). In a Josephson junction made on the TI surface, the spin-momentum locking of the TSS guarantees the existence of spin nondegenerate, perfectly transmitted Andreev modes. These modes lead to gap closing as a function of the superconducting phase difference φ. Here, we report the observation of highly transmissive Andreev modes in a TI Josephson junction, probed via tunnel contacts and φ controlled by a flux loop. Within our experimental resolution, they could indicate a gap closing and reopening. This phenomenon is observed for a wide range of chemical potentials, supporting its TSS origin. Under an applied magnetic field, highly transmissive modes are observed locally, matching theoretical predictions for Josephson vortices in the TSS. Our results support the fundamental role of spin-momentum locking in the Andreev physics in the TSS.
SN - 2375-2548
ER -