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.

  • Letter
  • Published:

Tunnelling spectroscopy of Andreev states in graphene

Nature Physics volume 13, pages 756–760 (2017)Cite this article

Subjects

Abstract

A normal conductor placed in good contact with a superconductor can inherit its remarkable electronic properties1,2. This proximity effect microscopically originates from the formation in the conductor of entangled electron–hole states, called Andreev states3,4,5,6,7,8. Spectroscopic studies of Andreev states have been performed in just a handful of systems9,10,11,12,13. The unique geometry, electronic structure and high mobility of graphene14,15 make it a novel platform for studying Andreev physics in two dimensions. Here we use a full van der Waals heterostructure to perform tunnelling spectroscopy measurements of the proximity effect in superconductor–graphene–superconductor junctions. The measured energy spectra, which depend on the phase difference between the superconductors, reveal the presence of a continuum of Andreev bound states. Moreover, our device heterostructure geometry and materials enable us to measure the Andreev spectrum as a function of the graphene Fermi energy, showing a transition between different mesoscopic regimes. Furthermore, by experimentally introducing a novel concept, the supercurrent spectral density, we determine the supercurrent–phase relation in a tunnelling experiment, thus establishing the connection between Andreev physics at finite energy and the Josephson effect. This work opens up new avenues for probing exotic topological phases of matter in hybrid superconducting Dirac materials16,17,18.

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

Access options

Buy this article

  • Purchase on SpringerLink
  • Instant access to the full article PDF.

USD 39.95

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

Figure 1: Experimental concept and device schematic.
Figure 2: Phase dependence of the graphene DOS.
Figure 3: Gate dependence of the graphene proximitized DOS.
Figure 4: Andreev states, supercurrent spectral density, and supercurrent in graphene.

Similar content being viewed by others

References

  1. Josephson, B. D. Possible new effects in superconductive tunnelling. Phys. Lett. 1, 251–253 (1962).

    Article  ADS  Google Scholar 

  2. De Gennes, P. G. Boundary effects in superconductors. Rev. Mod. Phys. 36, 225–237 (1964).

    Article  ADS  Google Scholar 

  3. Kulik, I. O. Macroscopic quantization and the proximity effect in S–N–S junctions. Sov. Phys. JETP 30, 944–950 (1970).

    ADS  Google Scholar 

  4. Furusaki, A. & Tsukada, M. Dc Josephson effect and Andreev reflection. Solid State Commun. 78, 299–302 (1991).

    Article  ADS  Google Scholar 

  5. Beenakker, C. W. J. & van Houten, H. Josephson current through a superconducting quantum point contact shorter than the coherence length. Phys. Rev. Lett. 66, 3056–3059 (1991).

    Article  ADS  Google Scholar 

  6. Bagwell, P. F. Suppression of the Josephson current through a narrow, mesoscopic, semiconductor channel by a single impurity. Phys. Rev. B 46, 12573–12586 (1992).

    Article  ADS  Google Scholar 

  7. Wendin, G. & Shumeiko, V. S. Josephson transport in complex mesoscopic structures. Superlattices Microstruct. 20, 569–573 (1996).

    Article  ADS  Google Scholar 

  8. Samuelsson, P., Lantz, J., Shumeiko, V. S. & Wendin, G. Nonequilibrium Josephson current in ballistic multiterminal SNS junctions. Phys. Rev. B 62, 1319–1337 (2000).

    Article  ADS  Google Scholar 

  9. Le Sueur, H., Joyez, P., Pothier, H., Urbina, C. & Esteve, D. Phase controlled superconducting proximity effect probed by tunneling spectroscopy. Phys. Rev. Lett. 100, 197002 (2008).

    Article  ADS  Google Scholar 

  10. Pillet, J.-D. et al. Revealing the electronic structure of a carbon nanotube carrying a supercurrent. Nat. Phys. 6, 965–969 (2010).

    Article  Google Scholar 

  11. Chang, W., Manucharyan, V. E., Jespersen, T. S., Nygård, J. & Marcus, C. M. Tunneling spectroscopy of quasiparticle bound states in a spinful Josephson junction. Phys. Rev. Lett. 110, 217005 (2013).

    Article  ADS  Google Scholar 

  12. Bretheau, L., Girit, Ç. Ö., Pothier, H., Esteve, D. & Urbina, C. Exciting Andreev pairs in a superconducting atomic contact. Nature 499, 312–315 (2013).

    Article  ADS  Google Scholar 

  13. Bretheau, L., Girit, Ç. Ö., Urbina, C., Esteve, D. & Pothier, H. Supercurrent spectroscopy of Andreev states. Phys. Rev. X 3, 041034 (2013).

    Google Scholar 

  14. Castro Neto, A. H., Guinea, F., Peres, N. M. R., Novoselov, K. S. & Geim, A. K. The electronic properties of graphene. Rev. Mod. Phys. 81, 109–162 (2009).

    Article  ADS  Google Scholar 

  15. Das Sarma, S., Adam, S., Hwang, E. H. & Rossi, E. Electronic transport in two-dimensional graphene. Rev. Mod. Phys. 83, 407–470 (2011).

    Article  ADS  Google Scholar 

  16. Lindner, N. H., Berg, E., Refael, G. & Stern, A. Fractionalizing majorana fermions: Non-abelian statistics on the edges of abelian quantum Hall states. Phys. Rev. X 2, 041002 (2012).

    Google Scholar 

  17. Clarke, D. J., Alicea, J. & Shtengel, K. Exotic non-abelian anyons from conventional fractional quantum Hall states. Nat. Commun. 4, 1348 (2013).

    Article  ADS  Google Scholar 

  18. San-Jose, P., Aguado, R., Guinea, F., Fernandez-Rossier, J. & Lado, J. Majorana zero modes in graphene. Phys. Rev. X 5, 041042 (2015).

    Google Scholar 

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

    Article  ADS  Google Scholar 

  20. Ben Shalom, M. et al. Quantum oscillations of the critical current and high-field superconducting proximity in ballistic graphene. Nat. Phys. 12, 318–322 (2015).

    Article  Google Scholar 

  21. Heersche, H. B., Jarillo-Herrero, P., Oostinga, J. B., Vandersypen, L. M. K. & Morpurgo, A. F. Bipolar supercurrent in graphene. Nature 446, 56–59 (2007).

    Article  ADS  Google Scholar 

  22. Du, X., Skachko, I. & Andrei, E. Y. Josephson current and multiple Andreev reflections in graphene SNS junctions. Phys. Rev. B 77, 184507 (2008).

    Article  ADS  Google Scholar 

  23. Girit, Ç. et al. Tunable graphene dc superconducting quantum interference device. Nano Lett. 9, 198–199 (2009).

    Article  ADS  Google Scholar 

  24. Dirks, T. et al. Transport through Andreev bound states in a graphene quantum dot. Nat. Phys. 7, 386–390 (2011).

    Article  Google Scholar 

  25. Komatsu, K., Li, C., Autier-Laurent, S., Bouchiat, H. & Guéron, S. Superconducting proximity effect in long superconductor/graphene/superconductor junctions: from specular Andreev reflection at zero field to the quantum Hall regime. Phys. Rev. B 86, 115412 (2012).

    Article  ADS  Google Scholar 

  26. Allen, M. T. et al. Spatially resolved edge currents and guided-wave electronic states in graphene. Nat. Phys. 12, 128–133 (2015).

    Article  Google Scholar 

  27. Efetov, D. K. et al. Specular interband Andreev reflections at van der Waals interfaces between graphene and NbSe2 . Nat. Phys. 12, 328–332 (2015).

    Article  Google Scholar 

  28. Natterer, F. D. et al. Scanning tunneling spectroscopy of proximity superconductivity in epitaxial multilayer graphene. Phys. Rev. B 93, 045406 (2016).

    Article  ADS  Google Scholar 

  29. Amet, F. et al. Supercurrent in the quantum Hall regime. Science 352, 966–969 (2016).

    Article  ADS  MathSciNet  Google Scholar 

  30. Beenakker, C. W. J. Specular Andreev reflection in graphene. Phys. Rev. Lett. 97, 067007 (2006).

    Article  ADS  Google Scholar 

  31. Lodder, A. & Nazarov, Y. V. Density of states and the energy gap in Andreev billiards. Phys. Rev. B 58, 5783–5788 (1998).

    Article  ADS  Google Scholar 

  32. Martin, J. et al. Observation of electron–hole puddles in graphene using a scanning single-electron transistor. Nat. Phys. 4, 144–148 (2008).

    Article  Google Scholar 

  33. Xue, J. M. et al. Scanning tunnelling microscopy and spectroscopy of ultra-flat graphene on hexagonal boron nitride. Nat. Mater. 10, 282–285 (2011).

    Article  ADS  Google Scholar 

  34. van Wees, B. J., Lenssen, K. M. H. & Harmans, C. J. P. M. Transmission formalism for supercurrent flow in multiprobe superconductor-semiconductor-superconductor devices. Phys. Rev. B 44, 470–473 (1991).

    Article  ADS  Google Scholar 

  35. Wilhelm, F. K., Schön, G. & Zaikin, A. D. Mesoscopic superconducting-normal metal-superconducting transistor. Phys. Rev. Lett. 81, 1682–1685 (1998).

    Article  ADS  Google Scholar 

  36. Baselmans, J. J. A., Morpurgo, A. F., van Wees, B. J. & Klapwijk, T. M. Reversing the direction of the supercurrent in a controllable Josephson junction. Nature 397, 43–45 (1999).

    Article  ADS  Google Scholar 

  37. Baselmans, J. J. A., Heikkilä, T. T., van Wees, B. J. & Klapwijk, T. M. Direct observation of the transition from the conventional superconducting state to the pi state in a controllable Josephson junction. Phys. Rev. Lett. 89, 207002 (2002).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  39. Wang, J. I. et al. Electronic transport of encapsulated graphene and WSe2 devices fabricated by pick-up of prepatterned hBN. Nano Lett. 15, 1898–1903 (2015).

    Article  ADS  Google Scholar 

  40. Spietz, L., Teufel, J. & Schoelkopf, R. J. A twisted pair cryogenic filter. Preprint at http://arXiv.org/abs/cond-mat/0601316 1–12 (2006).

Download references

Acknowledgements

We acknowledge helpful discussions with W. Belzig, J. C. Cuevas, V. Fatemi, Ç. Girit, P. Joyez, A. L. Yeyati, J.-D. Pillet, H. Pothier, V. Shumeiko and C. Urbina. This work has been primarily supported by the US DOE, BES Office, Division of Materials Sciences and Engineering under Award DE-SC0001819 and by the Gordon and Betty Moore Foundation’s EPiQS Initiative through Grant GBMF4541 to P.J.-H. J.I.-J.W. was partially supported by a Taiwan Merit Scholarship TMS-094-1-A-001. This work made use of the MRSEC Shared Experimental Facilities supported by NSF under award No. DMR-0819762 and of Harvard’s CNS, supported by NSF under Grant ECS-0335765.

Author information

Author notes

  1. Landry Bretheau and Joel I-Jan Wang: These authors contributed equally to this work.

Authors and Affiliations

  1. Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA

    Landry Bretheau, Joel I-Jan Wang, Riccardo Pisoni & Pablo Jarillo-Herrero

  2. National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan

    Kenji Watanabe & Takashi Taniguchi

Authors
  1. Landry Bretheau
    View author publications

    Search author on:PubMed Google Scholar

  2. Joel I-Jan Wang
    View author publications

    Search author on:PubMed Google Scholar

  3. Riccardo Pisoni
    View author publications

    Search author on:PubMed Google Scholar

  4. Kenji Watanabe
    View author publications

    Search author on:PubMed Google Scholar

  5. Takashi Taniguchi
    View author publications

    Search author on:PubMed Google Scholar

  6. Pablo Jarillo-Herrero
    View author publications

    Search author on:PubMed Google Scholar

Contributions

J.I.-J.W., L.B. and P.J.-H. designed the experiment. J.I.-J.W. and R.P. fabricated the devices. L.B. and J.I.-J.W. carried out the measurements. L.B. analysed and interpreted the data. K.W. and T.T. supplied hBN crystals. L.B. and J.I.-J.W. wrote the manuscript with input from all the authors.

Corresponding authors

Correspondence to Landry Bretheau, Joel I-Jan Wang or Pablo Jarillo-Herrero.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 7793 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Bretheau, L., Wang, JJ., Pisoni, R. et al. Tunnelling spectroscopy of Andreev states in graphene. Nature Phys 13, 756–760 (2017). https://doi.org/10.1038/nphys4110

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue date:

  • DOI: https://doi.org/10.1038/nphys4110

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