Tunable superconducting diode effect in a topological nano-SQUID

Ella Nikodem; Jakob Schluck; Max Geier; Michał Papaj; Henry F. Legg; Junya Feng; Mahasweta Bagchi; Liang Fu; Yoichi Ando

doi:10.1126/sciadv.adw4898

Tunable superconducting diode effect in a topological nano-SQUID

Ella Nikodem, Jakob Schluck, Max Geier, Michał Papaj, Henry F. Legg, Junya Feng, Mahasweta Bagchi, Liang Fu, Yoichi Ando^*

^*Corresponding author for this work

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

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. The sign and the magnitude of η are 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–superconducting quantum interference device (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.

Original language	English
Article number	eadw4898
Pages (from-to)	1-7
Number of pages	7
Journal	Science Advances
Volume	11
Issue number	38
DOIs	https://doi.org/10.1126/sciadv.adw4898
Publication status	Published - 19 Sept 2025

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Dataset for "Tunable superconducting diode effect in a topological nano-SQUID"
Nikodem, E. (Creator), Schluck, J. (Creator), Geier, M. (Creator), Papaj, M. (Creator), Legg, H. (Creator), Feng, J. (Creator), Bagchi, M. (Creator), Fu, L. (Creator) & Ando, Y. (Creator), Zenodo, 2025
DOI: 10.5281/zenodo.14576331
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title = "Tunable superconducting diode effect in a topological nano-SQUID",

abstract = "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. The sign and the magnitude of η are 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–superconducting quantum interference device (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.",

author = "Ella Nikodem and Jakob Schluck and Max Geier and Micha{\l} Papaj and Legg, {Henry F.} and Junya Feng and Mahasweta Bagchi and Liang Fu and Yoichi Ando",

note = "Funding: This project has received funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation program (grant agreement no. 741121) and was also funded by the Deutsche Forschungsgemeinschaft (DFG; German Research Foundation) under Germany{\textquoteright}s Excellence Strategy - Cluster of Excellence Matter and Light for Quantum Computing (ML4Q) EXC 2004/1 - 390534769, as well as by the DFG under CRC 1238 - 277146847 (subprojects A04 and B01). E.N. acknowledges support by the Studienstiftung des deutschen Volkes. This work was completed in part with resources provided by the Research Computing Data Core at the University of Houston. M.G. acknowledges support from the German Research Foundation under the Walter Benjamin program (grant agreement no. 526129603). L.F. is partly supported by a Simons Investigator Award from the Simons Foundation.",

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AU - Nikodem, Ella

AU - Schluck, Jakob

AU - Geier, Max

AU - Papaj, Michał

AU - Legg, Henry F.

AU - Feng, Junya

AU - Bagchi, Mahasweta

AU - Fu, Liang

AU - Ando, Yoichi

N1 - Funding: This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement no. 741121) and was also funded by the Deutsche Forschungsgemeinschaft (DFG; German Research Foundation) under Germany’s Excellence Strategy - Cluster of Excellence Matter and Light for Quantum Computing (ML4Q) EXC 2004/1 - 390534769, as well as by the DFG under CRC 1238 - 277146847 (subprojects A04 and B01). E.N. acknowledges support by the Studienstiftung des deutschen Volkes. This work was completed in part with resources provided by the Research Computing Data Core at the University of Houston. M.G. acknowledges support from the German Research Foundation under the Walter Benjamin program (grant agreement no. 526129603). L.F. is partly supported by a Simons Investigator Award from the Simons Foundation.

PY - 2025/9/19

Y1 - 2025/9/19

N2 - 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. The sign and the magnitude of η are 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–superconducting quantum interference device (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.

AB - 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. The sign and the magnitude of η are 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–superconducting quantum interference device (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.

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Tunable superconducting diode effect in a topological nano-SQUID

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