Abstract
Superconductivity serves as a basis for non-trivial quantum phenomena and devices, but they often require artificial control of the superconducting gap. In real space, there are various ways to tailor the superconducting gap, such as by introducing interfaces and defects. However, it is challenging to manipulate the superconducting gap in momentum space. Here we demonstrate that the superconducting gap of NbSe2 monolayers on graphene can be modified at specific momenta by changing the twist angle between the layers. Our spectroscopic-imaging-based scanning tunnelling microscopy experiments reveal the interference patterns of Bogoliubov quasiparticles that are twisted with respect to NbSe2 and graphene lattices. We find that these chiral interference patterns originate from the twist-dependent sextet of regions in momentum space in which the Fermi surfaces of the NbSe2 monolayer and graphene overlap. This finding not only broadens our understanding of superconductivity in twisted bilayer systems but also opens up possibilities for designing artificial superconducting materials and devices with tunable properties.
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Fig. 1: STM characterizations of NbSe2 atomic layers grown on graphene.
Fig. 2: Moiré and QPI modulations in the NbSe2 monolayer on graphene with θ = 28°.
Fig. 3: Superconducting gap of the NbSe2 monolayer on graphene with θ = 28°.
Fig. 4: Twisted Bogoliubov quasiparticles.
Fig. 5: Sextet model of the twisted Bogoliubov QPI.
Fig. 6: Simulated Bogoliubov QPI patterns in the twisted stacks.
Data availability
Additional data supporting the findings of this study are available from the corresponding authors upon reasonable request. Source data are provided with this paper.
Code availability
The codes supporting the findings of this study are available from the corresponding authors upon reasonable request.
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Acknowledgements
We thank C. J. Butler, M. Nakano, K. Sugawara, Y. Okada, Y. Hasegawa and P. Wahl for valuable discussions and comments. This work was supported by the RIKEN TRIP initiative (Many-Body Electron Systems) and JSPS KAKENHI grant nos. JP19H05824, JP21K18145, JP22H04933, JP22K18696, JP22K20362, JP23K13067, JP23K17353, JP23K22452, JP23K25831 JP24H00007, JP24K21530 and JST PRESTO JPMJPR19L8. M.N. acknowledges support from RIKEN’s SPDR fellowship.
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Authors and Affiliations
RIKEN Center for Emergent Matter Science, Wako, Japan
Masahiro Naritsuka, Tadashi Machida & Tetsuo Hanaguri
Department of Physics, Kyoto University, Kyoto, Japan
Shun Asano & Youichi Yanase
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Masahiro Naritsuka
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2. Tadashi Machida
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3. Shun Asano
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4. Youichi Yanase
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Contributions
M.N. prepared the samples, carried out the SI-STM measurements and analysed the data with assistance from T.M. S.A. and Y.Y. contributed to the construction of the sextet model. T.H. supervised the project. M.N. and T.H. wrote the manuscript. All authors discussed the results and contributed to finalizing the manuscript.
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Correspondence to Masahiro Naritsuka or Tetsuo Hanaguri.
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Naritsuka, M., Machida, T., Asano, S. et al. Superconductivity controlled by twist angle in monolayer NbSe2 on graphene. Nat. Phys. (2025). https://doi.org/10.1038/s41567-025-02828-6
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Received:05 June 2024
Accepted:10 February 2025
Published:20 March 2025
DOI:https://doi.org/10.1038/s41567-025-02828-6
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