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General Framework Enabling Polarity-Tunable Time-Reversal Symmetric Superconducting Diode Effects in Gate-Defined Homojunctions

Hongwei Zhang1,2,3,*, Chunsheng Wang1,2,*, Ran Wang1,2,*, Senyang Pan1, Hengning Wang1,2, Jiaqiang Cai1,2, Yonglai Liu1,2, Zhe Qu1, Xiangde Zhu1 et al.

Wei Ning1, Chuanying Xi1, Jinglei Zhang1, Ning Hao1,†, Guolin Zheng1,‡, and Mingliang Tian1,4,5,§

  • *These authors contributed equally to this paper.
  • †Contact author: haon@hmfl.ac.cn
  • ‡Contact author: glzheng@hmfl.ac.cn
  • §Contact author: tianml@hmfl.ac.cn
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Phys. Rev. X 16, 021046 – Published 29 May, 2026

DOI: https://doi.org/10.1103/wm2k-vlvc

Abstract

Symmetry breaking underlies various nonreciprocal transport phenomena. A well-known example is the semiconductor p−n junction diode, a cornerstone of modern electronics. Its superconducting counterpart—the superconducting diode effect (SDE)—has recently attracted intense interest due to its potential in ultra-low-power superconducting circuits. While most SDEs reported so far involve either explicit or spontaneous breaking of time-reversal symmetry (TRS), a comprehensive theoretical framework remains elusive. Moreover, a general mechanism enabling TRS-preserving SDEs with minimal dependence on material or device architecture has yet to be established. Here, we report polarity-tunable SDEs without breaking TRS, realized in superconducting n−n, p−n, and p−p homojunctions defined via local protonic gates in multilayer NbSe2. The local gates induce partial proton intercalation, generating a built-in proton concentration gradient across the transition zone between the gated and ungated regions—closely resembling the depletion layer in conventional semiconductor diodes. We find that the observed SDE arises from electric-field-driven variation of the proton concentration gradient in the transition region, which asymmetrically modulates the critical current: suppressing it in one direction and enhancing it in the other. This local-gate-driven, TRS-preserving mechanism offers a general and scalable strategy for realizing nonreciprocal superconducting transport. Our findings establish a material-agnostic platform for SDEs, broadly applicable across two-dimensional (2D) superconductors.

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Physics Subject Headings (PhySH)

Corrections

1 July, 2026

Correction: The author contribution statement was missing and has been added. A statement of thanks was missing from the Acknowledgments section and has been inserted.

Popular Summary

Developing efficient superconducting diodes usually requires the breaking of time-reversal symmetry via external magnetic fields or magnetic proximity effects, which can complicate the integration of these components into scalable electronic architectures. We addressed this challenge by demonstrating a time-reversal symmetric superconducting diode effect in NbSe2 homojunctions defined by local protonic gates. Our study shows that a built-in proton concentration gradient across the junction allows for electric-field-driven proton displacement, which asymmetrically modulates the critical current in opposite directions. We successfully implemented this mechanism in n−n, p−n, and p−p junction configurations, confirming that the diode behavior persists without the need for magnetic field bias. These results establish a platform for creating nonreciprocal superconducting components using ionic gating. Our work provides a scalable pathway for developing dissipationless logic and memory devices based on two-dimensional superconductors.

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Outline

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Phys. Rev. X 16, 021046– Published 29 May, 2026
  • Received 10 September 2025
  • Revised 5 February 2026
  • Accepted 27 April 2026
  • Corrected 1 July 2026
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