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Ballistic Josephson junctions in edge-contacted graphene

Abstract

Hybrid graphene–superconductor devices have attracted much attention since the early days of graphene research1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18. So far, these studies have been limited to the case of diffusive transport through graphene with poorly defined and modest-quality graphene/superconductor interfaces, usually combined with small critical magnetic fields of the superconducting electrodes. Here, we report graphene-based Josephson junctions with one-dimensional edge contacts19 of molybdenum rhenium. The contacts exhibit a well-defined, transparent interface to the graphene, have a critical magnetic field of 8 T at 4 K, and the graphene has a high quality due to its encapsulation in hexagonal boron nitride19,20. This allows us to study and exploit graphene Josephson junctions in a new regime, characterized by ballistic transport. We find that the critical current oscillates with the carrier density due to phase-coherent interference of the electrons and holes that carry the supercurrent caused by the formation of a Fabry–Pérot cavity. Furthermore, relatively large supercurrents are observed over unprecedented long distances of up to 1.5 μm. Finally, in the quantum Hall regime we observe broken symmetry states while the contacts remain superconducting. These achievements open up new avenues to exploit the Dirac nature of graphene in interaction with the superconducting state.

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Figure 1: High-quality hBN–graphene–hBN devices.
Figure 2: Long-distance Josephson current in edge-contacted graphene.
Figure 3: Fabry–Pérot resonances in a Josephson junction.
Figure 4: Anomalous Fraunhofer diffraction pattern.

References

  1. 1

    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).

    CAS  Article  Google Scholar 

  2. 2

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

    Article  Google Scholar 

  3. 3

    Miao, F., Bao, W., Zhang, H. & Lau, C. N. Premature switching in graphene Josephson transistors. Solid State Commun. 149, 1046–1049 (2009).

    CAS  Article  Google Scholar 

  4. 4

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

    CAS  Article  Google Scholar 

  5. 5

    Ojeda-Aristizabal, C., Ferrier, M., Guéron, S. & Bouchiat, H. Tuning the proximity effect in a superconductor–graphene–superconductor junction. Phys. Rev. B 79, 165436 (2009).

    Article  Google Scholar 

  6. 6

    Kanda, A. et al. Dependence of proximity-induced supercurrent on junction length in multilayer-graphene Josephson junctions. Phys. C (Amsterdam, Neth.) 470, 1477–1480 (2010).

    CAS  Article  Google Scholar 

  7. 7

    Choi, J.-H., Lee, H.-J. & Doh, Y.-J. Above-gap conductance anomaly studied in superconductor–graphene–superconductor Josephson junctions. J. Korean Phys. Soc. 57, 149 (2010).

    CAS  Article  Google Scholar 

  8. 8

    Borzenets, I. V., Coskun, U. C., Jones, S. J. & Finkelstein, G. Phase diffusion in graphene-based Josephson junctions. Phys. Rev. Lett. 107, 137005 (2011).

    CAS  Article  Google Scholar 

  9. 9

    Coskun, U. C. et al. Distribution of supercurrent switching in graphene under proximity effect. Phys. Rev. Lett. 108, 097003 (2012).

    CAS  Article  Google Scholar 

  10. 10

    Lee, G.-H., Jeong, D., Choi, J.-H., Doh, Y.-J. & Lee, H.-J. Electrically tunable macroscopic quantum tunneling in a graphene-based Josephson junction. Phys. Rev. Lett. 107, 146605 (2011).

    Article  Google Scholar 

  11. 11

    Rickhaus, P., Weiss, M., Marot, L. & Schönenberger, C. Quantum Hall effect in graphene with superconducting electrodes. Nano Lett. 12, 1942–1945 (2012).

    CAS  Article  Google Scholar 

  12. 12

    Popinciuc, M. et al. Zero-bias conductance peak and Josephson effect in graphene–NbTiN junctions. Phys. Rev. B 85, 205404 (2012).

    Article  Google Scholar 

  13. 13

    Komatsu, K., Li, C., Autier-Laurent, S., Bouchiat, H. & Gueron, S. Superconducting proximity effect through graphene from zero field to the quantum Hall regime. Phys. Rev. B 86, 115412 (2012).

    Article  Google Scholar 

  14. 14

    Mizuno, N., Nielsen, B. & Du, X. Ballistic-like supercurrent in suspended graphene Josephson weak links. Nature Commun. 4, 2716 (2013).

    Article  Google Scholar 

  15. 15

    Voutilainen, J. et al. Energy relaxation in graphene and its measurement with supercurrent. Phys. Rev. B 84, 045419 (2011).

    Article  Google Scholar 

  16. 16

    Jeong, D. et al. Observation of supercurrent in PbIn–graphene–PbIn Josephson junction. Phys. Rev. B 83, 094503 (2011).

    Article  Google Scholar 

  17. 17

    Borzenets, I. V. et al. Phonon bottleneck in graphene-based Josephson junctions at milli-Kelvin temperatures. Phys. Rev. Lett. 111, 027001 (2013).

    CAS  Article  Google Scholar 

  18. 18

    Choi, J.-H. et al. Complete gate control of supercurrent in graphene p–n junctions. Nature Commun. 4, 2525 (2013).

    Article  Google Scholar 

  19. 19

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

    CAS  Article  Google Scholar 

  20. 20

    Dean, C. R. et al. Boron nitride substrates for high-quality graphene electronics. Nature Nanotech. 5, 722–726 (2010).

    CAS  Article  Google Scholar 

  21. 21

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

    CAS  Article  Google Scholar 

  22. 22

    Hoppe, H., Zülicke, U. & Schön, G. Andreev reflection in strong magnetic fields. Phys. Rev. Lett. 84, 1804–1807 (2000).

    CAS  Article  Google Scholar 

  23. 23

    Chtchelkatchev, N. M. & Burmistrov, I. S. Conductance oscillations with magnetic field of a two-dimensional electron gas–superconductor junction. Phys. Rev. B 75, 214510 (2007).

    Article  Google Scholar 

  24. 24

    Akhmerov, A. R. & Beenakker, C. W. J. Detection of valley polarization in graphene by a superconducting contact. Phys. Rev. Lett. 98, 157003 (2007).

    CAS  Article  Google Scholar 

  25. 25

    Martin, I., Blanter, Y. M. & Morpurgo, A. F. Topological confinement in bilayer graphene. Phys. Rev. Lett. 100, 036804 (2008).

    Article  Google Scholar 

  26. 26

    Du, X., Skachko, I., Barker, A. & Andrei, E. Y. Approaching ballistic transport in suspended graphene. Nature Nanotech. 3, 491–495 (2008).

    CAS  Article  Google Scholar 

  27. 27

    Schneider, B. H., Etaki, S., van der Zant, H. S. J. & Steele, G. A. Coupling carbon nanotube mechanics to a superconducting circuit. Sci. Rep. 2, 599 (2012).

    CAS  Article  Google Scholar 

  28. 28

    Maher, P. et al. Tunable fractional quantum Hall phases in bilayer graphene. Science 345, 61–64 (2014).

    CAS  Article  Google Scholar 

  29. 29

    Young, A. F. & Kim, P. Quantum interference and Klein tunnelling in graphene heterojunctions. Nature Phys. 5, 222–226 (2009).

    CAS  Article  Google Scholar 

  30. 30

    Varlet, A. et al. Fabry–Pérot interference in gapped bilayer graphene with broken anti-Klein tunneling. Phys. Rev. Lett. 113, 116601 (2014).

    Article  Google Scholar 

  31. 31

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

    Google Scholar 

  32. 32

    Heida, J. P., van Wees, B. J., Klapwijk, T. M. & Borghs, G. Nonlocal supercurrent in mesoscopic Josephson junctions. Phys. Rev. B 57, R5618–R5621 (1998).

    CAS  Article  Google Scholar 

  33. 33

    Ledermann, U., Fauchère, A. L. & Blatter, G. Nonlocality in mesoscopic Josephson junctions with strip geometry. Phys. Rev. B 59, R9027–R9030 (1999).

    CAS  Article  Google Scholar 

  34. 34

    Sheehy, D. E. & Zagoskin, A. M. Theory of anomalous magnetic interference pattern in mesoscopic superconducting/normal/superconducting Josephson junctions. Phys. Rev. B 68, 144514 (2003).

    Article  Google Scholar 

  35. 35

    Groth, C. W., Wimmer, M., Akhmerov, A. R., & Waintal, X. Kwant: a software package for quantum transport. New J. Phys. 16, 063065 (2014).

    Article  Google Scholar 

Download references

Acknowledgements

The authors thank V. Singh for sharing the MoRe sputtering recipe and C. Beenakker for discussions. The authors acknowledge support from the EC-FET Graphene Flagship, from the European Research Council (advanced grant no. 339306; METIQUM), from a European Research Council Synergy grant (QC-LAB) and from the Ministry of Education and Science of the Russian Federation (contract no. 14.B25.31.0007). This work is part of the Nanofront Consortium, funded by the Dutch Science Foundation OCW/NWO/FOM.

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K.W. and T.T. grew the hBN crystals, G.N. fabricated the devices, V.E.C. and S.G. performed the measurements, and M.D. and A.R.A. carried out the numerical simulations and theory. The measurements were analysed and interpreted by V.E.C., S.G., M.D., A.R.A., T.M.K. and L.M.K.V. The manuscript was written by V.E.C., S.G. and L.M.K.V., with input from A.R.A., M.D. and T.M.K.

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Correspondence to L. M. K. Vandersypen.

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The authors declare no competing financial interests.

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Calado, V., Goswami, S., Nanda, G. et al. Ballistic Josephson junctions in edge-contacted graphene. Nature Nanotech 10, 761–764 (2015). https://doi.org/10.1038/nnano.2015.156

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