Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Highly tunable junctions and non-local Josephson effect in magic-angle graphene tunnelling devices

Nature Nanotechnology volume 16, pages 769–775 (2021)Cite this article

Subjects

Abstract

Magic-angle twisted bilayer graphene (MATBG) has recently emerged as a highly tunable two-dimensional material platform exhibiting a wide range of phases, such as metal, insulator and superconductor states. Local electrostatic control over these phases may enable the creation of versatile quantum devices that were previously not achievable in other single-material platforms. Here we engineer Josephson junctions and tunnelling transistors in MATBG, solely defined by electrostatic gates. Our multi-gated device geometry offers independent control of the weak link, barriers and tunnelling electrodes. These purely two-dimensional MATBG Josephson junctions exhibit non-local electrodynamics in a magnetic field, in agreement with the Pearl theory for ultrathin superconductors. Utilizing the intrinsic bandgaps of MATBG, we also demonstrate monolithic edge tunnelling spectroscopy within the same MATBG devices and measure the energy spectrum of MATBG in the superconducting phase. Furthermore, by inducing a double-barrier geometry, the devices can be operated as a single-electron transistor, exhibiting Coulomb blockade. With versatile functionality encompassed within a single material, these MATBG tunnelling devices may find applications in graphene-based tunable superconducting qubits, on-chip superconducting circuits and electromagnetic sensing.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Device A structure and transport characterization.
Fig. 2: Comparison of planar 2D and bulk JJs.
Fig. 3: Non-locality and tunability of MATBG JJs.
Fig. 4: Edge tunnelling spectroscopy of the superconducting gap in MATBG.
Fig. 5: Electrostatically defined SET and Coulomb blockade in MATBG.

Similar content being viewed by others

Data availability

Source data are provided with this paper. The data that support the findings of this study are available from the corresponding authors upon reasonable request.

References

  1. Tinkham, M. Introduction to Superconductivity 2nd edn (Dover Publications, 2004).

  2. Likharev, K. K. Superconducting weak links. Rev. Mod. Phys. 51, 101–159 (1979).

    Article  Google Scholar 

  3. Oliver, W. D. & Welander, P. B. Materials in superconducting quantum bits. MRS Bull. 38, 816–825 (2013).

    Article  CAS  Google Scholar 

  4. Larsen, T. et al. Semiconductor-nanowire-based superconducting qubit. Phys. Rev. Lett. 115, 127001 (2015).

    Article  CAS  Google Scholar 

  5. Wang, J. I.-J. et al. Coherent control of a hybrid superconducting circuit made with graphene-based van der Waals heterostructures. Nat. Nanotechnol. 14, 120–125 (2019).

    Article  CAS  Google Scholar 

  6. Cao, Y. et al. Correlated insulator behaviour at half-filling in magic-angle graphene superlattices. Nature 556, 80–84 (2018).

    Article  CAS  Google Scholar 

  7. Cao, Y. et al. Unconventional superconductivity in magic-angle graphene superlattices. Nature 556, 43–50 (2018).

    Article  CAS  Google Scholar 

  8. Yankowitz, M. et al. Tuning superconductivity in twisted bilayer graphene. Science 363, 1059–1064 (2019).

    Article  CAS  Google Scholar 

  9. Lu, X. et al. Superconductors, orbital magnets and correlated states in magic-angle bilayer graphene. Nature 574, 653–657 (2019).

    Article  CAS  Google Scholar 

  10. Li, G. et al. Observation of Van Hove singularities in twisted graphene layers. Nat. Phys. 6, 109–113 (2010).

    Article  Google Scholar 

  11. Surez Morell, E., Correa, J. D., Vargas, P., Pacheco, M. & Barticevic, Z. Flat bands in slightly twisted bilayer graphene: tight-binding calculations. Phys. Rev. B 82, 121407 (2010).

    Article  Google Scholar 

  12. Bistritzer, R. & MacDonald, A. H. Moiré bands in twisted double-layer graphene. Proc. Natl Acad. Sci. USA 108, 12233–12237 (2011).

    Article  CAS  Google Scholar 

  13. Lopes dos Santos, J. M. B., Peres, N. M. R. & Castro Neto, A. H. Continuum model of the twisted graphene bilayer. Phys. Rev. B 86, 155449 (2012).

    Article  Google Scholar 

  14. Kim, K. et al. van der Waals heterostructures with high accuracy rotational alignment. Nano Lett. 16, 1989–1995 (2016).

    Article  CAS  Google Scholar 

  15. Cao, Y. et al. Superlattice-induced insulating states and valley-protected orbits in twisted bilayer graphene. Phys. Rev. Lett. 117, 116804 (2016).

    Article  CAS  Google Scholar 

  16. Kim, K. et al. Tunable moiré bands and strong correlations in small-twist-angle bilayer graphene. Proc. Natl Acad. Sci. USA 114, 3364–3369 (2017).

    Article  CAS  Google Scholar 

  17. Nam, N. N. T. & Koshino, M. Lattice relaxation and energy band modulation in twisted bilayer graphene. Phys. Rev. B 96, 075311 (2017).

    Article  Google Scholar 

  18. Pearl, J. Current distribution in superconducting films carrying quantized fluxoids. Appl. Phys. Lett. 5, 65–66 (1964).

    Article  Google Scholar 

  19. Moshe, M., Kogan, V. G. & Mints, R. G. Edge-type Josephson junctions in narrow thin-film strips. Phys. Rev. B 78, 020510 (2008).

    Article  Google Scholar 

  20. Ivanchenko, Y. M. & Soboleva, T. K. Nonlocal interaction in Josephson junctions. Phys. Lett. A 147, 65–69 (1990).

    Article  Google Scholar 

  21. Boris, A. A. et al. Evidence for nonlocal electrodynamics in planar Josephson junctions. Phys. Rev. Lett. 111, 117002 (2013).

    Article  CAS  Google Scholar 

  22. Abdumalikov, A. A., Alfimov, G. L. & Malishevskii, A. S. Nonlocal electrodynamics of Josephson vortices in superconducting circuits. Supercond. Sci. Technol. 22, 023001 (2009).

    Article  Google Scholar 

  23. Clem, J. R. Josephson junctions in thin and narrow rectangular superconducting strips. Phys. Rev. B 81, 144515 (2010).

    Article  Google Scholar 

  24. Kogan, V. G., Dobrovitski, V. V., Clem, J. R., Mawatari, Y. & Mints, R. G. Josephson junction in a thin film. Phys. Rev. B 63, 144501 (2001).

    Article  Google Scholar 

  25. Rosenthal, P. A., Beasley, M. R., Char, K., Colclough, M. S. & Zaharchuk, G. Flux focusing effects in planar thin-film grain-boundary Josephson junctions. Appl. Phys. Lett. 59, 3482–3484 (1991).

    Article  CAS  Google Scholar 

  26. Nagata, S., Yang, H. C. & Finnemore, D. K. Oscillations in the temperature dependence of Josephson supercurrents in SNS junctions. Phys. Rev. B 25, 6012–6014 (1982).

    Article  CAS  Google Scholar 

  27. Calado, V. E. et al. Ballistic Josephson junctions in edge-contacted graphene. Nat. Nanotechnol. 10, 761–764 (2015).

    Article  CAS  Google Scholar 

  28. Ben Shalom, M. et al. Quantum oscillations of the critical current and high-field superconducting proximity in ballistic graphene. Nat. Phys. 12, 318–322 (2016).

    Article  Google Scholar 

  29. Efros, A. L. & Shklovskii, B. I. Coulomb gap and low temperature conductivity of disordered systems.J. Phys. C 8, L49–L51 (1975).

    Article  CAS  Google Scholar 

  30. Lee, M., Massey, J. G., Nguyen, V. L. & Shklovskii, B. I. Coulomb gap in a doped semiconductor near the metal-insulator transition: tunneling experiment and scaling ansatz. Phys. Rev. B 60, 1582–1591 (1999).

    Article  CAS  Google Scholar 

  31. Altshuler, B. L. & Aronov, A. G. Zero bias anomaly in tunnel resistance and electron-electron interaction. Solid State Commun. 88, 1033–1035 (1993).

    Article  Google Scholar 

  32. Gershenzon, M. E., Gubankov, V. N. & Falei, M. I. Tunnel spectroscopy of the electron-electron interaction in disordered aluminum films. Sov. Phys. JETP 63, 1287–1294 (1986).

    Google Scholar 

  33. Kotel’nikov, I. N., Dizhur, S. E., Morozova, E. N., Devyatov, E. V. & Dolgopolov, V. T. Zero-bias tunneling anomaly in a two-dimensional electron system with disorder. JETP Lett. 96, 577–581 (2013).

    Article  Google Scholar 

  34. Ihn, T. et al. Graphene single-electron transistors. Mater. Today 13, 44–50 (2010).

    Article  CAS  Google Scholar 

  35. de Vries, F. K. et al. Gate-defined Josephson junctions in magic-angle twisted bilayer graphene. Nat. Nanotechnol. https://doi.org/10.1038/s41565-021-00896-2 (2021).

  36. Wang, L. et al. One-dimensional electrical contact to a two-dimensional material. Science 342, 614–617 (2013).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

We acknowledge helpful discussions with L. Levitov, Z. Dong, W. D. Oliver, J. I.-J. Wang, M. A. Mueed and B. Skinner. This work has been supported by the National Science Foundation (NSF) through grant DMR-1809802 and by the STC Center for Integrated Quantum Materials (NSF grant no. DMR-1231319) for partial device fabrication, transport measurements and data analysis (Y.C., D.R.-L. and S.C.d.l.B.). Transport measurements and data analysis were supported by the US Department of Energy (DOE), Office of Basic Energy Sciences (BES), Division of Materials Sciences and Engineering under award DE-SC0001819 (J.M.P.). Partial support for conceptual development and device technology was provided by the US Army Research Office grant no. W911NF-17-S-0001 (D.R.-L). D.R.-L. acknowledges earlier support from Fundación Bancaria ‘la Caixa’ (LCF/BQ/AN15/10380011). P.J.-H. acknowledges support from the Gordon and Betty Moore Foundation’s EPiQS Initiative through grant GBMF9643 and general support by the Fundación Ramón Areces. The development of new nanofabrication and characterization techniques enabling this work has been supported by the US DOE Office of Science, BES, under award DE-SC0019300. M.T.R. acknowledges support from the MIT Pappalardo Fellowship. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan, grant number JPMXP0112101001, JSPS KAKENHI grant number JP20H00354 and CREST (JPMJCR15F3), JST. This work made use of the Materials Research Science and Engineering Center Shared Experimental Facilities supported by the NSF (DMR-0819762) and of Harvard’s Center for Nanoscale Systems, supported by the NSF (ECS-0335765).

Author information

Author notes

  1. These authors contributed equally: Daniel Rodan-Legrain, Yuan Cao, Jeong Min Park.

Authors and Affiliations

  1. Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA

    Daniel Rodan-Legrain, Yuan Cao, Jeong Min Park, Sergio C. de la Barrera, Mallika T. Randeria & Pablo Jarillo-Herrero

  2. National Institute for Materials Science, Tsukuba, Japan

    Kenji Watanabe & Takashi Taniguchi

Authors
  1. Daniel Rodan-Legrain
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Yuan Cao
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Jeong Min Park
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Sergio C. de la Barrera
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Mallika T. Randeria
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Kenji Watanabe
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Takashi Taniguchi
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Pablo Jarillo-Herrero
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

D.R.-L., Y.C. and J.M.P. fabricated the samples and performed the transport measurements. D.R.-L., Y.C., J.M.P., S.C.d.l.B., M.T.R. and P.J.-H. performed the data analysis and discussed the results. Y.C. performed the numerical simulations. P.J.-H supervised the project. K.W. and T.T. provided the hBN samples. D.R.-L., Y.C., J.M.P, S.C.d.l.B., M.T.R. and P.J.-H. co-wrote the manuscript with input from all co-authors.

Corresponding authors

Correspondence to Daniel Rodan-Legrain, Yuan Cao or Pablo Jarillo-Herrero.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature Nanotechnology thanks Xu Du and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary information.

Source data

Source Data Fig. 1

Fig. 1 data.

Source Data Fig. 2

Fig. 2 data.

Source Data Fig. 3

Fig. 3 data.

Source Data Fig. 4

Fig. 4 data.

Source Data Fig. 5

Fig. 5 data.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Rodan-Legrain, D., Cao, Y., Park, J.M. et al. Highly tunable junctions and non-local Josephson effect in magic-angle graphene tunnelling devices. Nat. Nanotechnol. 16, 769–775 (2021). https://doi.org/10.1038/s41565-021-00894-4

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41565-021-00894-4

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing