Letter | Published:

Realization of a tunable artificial atom at a supercritically charged vacancy in graphene

Nature Physics volume 12, pages 545549 (2016) | Download Citation

Abstract

Graphene’s remarkable electronic properties have fuelled the vision of a graphene-based platform for lighter, faster and smarter electronics and computing applications. One of the challenges is to devise ways to tailor graphene’s electronic properties and to control its charge carriers1,2,3,4,5. Here we show that a single-atom vacancy in graphene can stably host a local charge and that this charge can be gradually built up by applying voltage pulses with the tip of a scanning tunnelling microscope. The response of the conduction electrons in graphene to the local charge is monitored with scanning tunnelling and Landau level spectroscopy, and compared to numerical simulations. As the charge is increased, its interaction with the conduction electrons undergoes a transition into a supercritical regime6,7,8,9,10,11 where itinerant electrons are trapped in a sequence of quasi-bound states which resemble an artificial atom. The quasi-bound electron states are detected by a strong enhancement of the density of states within a disc centred on the vacancy site which is surrounded by halo of hole states. We further show that the quasi-bound states at the vacancy site are gate tunable and that the trapping mechanism can be turned on and off, providing a mechanism to control and guide electrons in graphene.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    , & Chiral tunnelling and the Klein paradox in graphene. Nature Phys. 2, 620–625 (2006).

  2. 2.

    , & Electronic properties of disordered two-dimensional carbon. Phys. Rev. B 73, 125411 (2006).

  3. 3.

    Screening effect and impurity scattering in monolayer graphene. J. Phys. Soc. Jpn 75, 074716 (2006).

  4. 4.

    , , & Electronic transport in two-dimensional graphene. Rev. Mod. Phys. 83, 407–470 (2011).

  5. 5.

    , , , & Electron–electron interactions in graphene: current status and perspectives. Rev. Mod. Phys. 84, 1067–1125 (2012).

  6. 6.

    & Dirac electron in a Coulomb field in (2 + 1) dimensions. Mod. Phys. Lett. A 13, 615–622 (1998).

  7. 7.

    , & Coulomb impurity problem in graphene. Phys. Rev. Lett. 99, 166802 (2007).

  8. 8.

    , & Vacuum polarization and screening of supercritical impurities in graphene. Phys. Rev. Lett. 99, 236801 (2007).

  9. 9.

    , & Atomic collapse and quasi–Rydberg states in graphene. Phys. Rev. Lett. 99, 246802 (2007).

  10. 10.

    , & Screening of a hypercritical charge in graphene. Phys. Rev. B 76, 233402 (2007).

  11. 11.

    et al. Observing atomic collapse resonances in artificial nuclei on graphene. Science 340, 734–737 (2013).

  12. 12.

    & On the energy levels of systems with Z > 1/137. J. Phys. 9, 97–100 (1945).

  13. 13.

    & Electronic structure of superheavy atoms. Sov. Phys. Usp. 14, 673–694 (1972).

  14. 14.

    et al. Mapping Dirac quasiparticles near a single Coulomb impurity on graphene. Nature Phys. 8, 653–657 (2012).

  15. 15.

    , & Adsorption of NH2 on graphene in the presence of defects and adsorbates. J. Phys. Chem. C 117, 2793–2798 (2013).

  16. 16.

    et al. Effects of ion bombardment on a two-dimensional target: Atomistic simulations of graphene irradiation. Phys. Rev. B 81, 153401 (2010).

  17. 17.

    , , , & Tunable Kondo effect in graphene with defects. Nature Phys. 7, 535–538 (2011).

  18. 18.

    , , , & Threefold electron scattering on graphite observed with C60-adsorbed STM tips. Science 273, 1371–1373 (1996).

  19. 19.

    , , & Missing atom as a source of carbon magnetism. Phys. Rev. Lett. 104, 096804 (2010).

  20. 20.

    , & Electronic properties of graphene: a perspective from scanning tunneling microscopy and magneto-transport. Rep. Prog. Phys. 75, 056501 (2012).

  21. 21.

    & Defect-induced magnetism in graphene. Phys. Rev. B 75, 125408 (2007).

  22. 22.

    , , , & Disorder induced localized states in graphene. Phys. Rev. Lett. 96, 036801 (2006).

  23. 23.

    , & Determining charge state of graphene vacancy by noncontact atomic force microscopy and first-principles calculations. Nanotechnology 26, 035702 (2015).

  24. 24.

    et al. Screening charged impurities and lifting the orbital degeneracy in graphene by populating Landau levels. Phys. Rev. Lett. 112, 036804 (2014).

  25. 25.

    , , & Controlling the charge state of individual gold adatoms. Science 305, 493–495 (2004).

  26. 26.

    et al. Controlling the Kondo effect of an adsorbed magnetic ion through its chemical bonding. Science 309, 1542–1544 (2005).

  27. 27.

    Vacuum polarization of graphene with a supercritical Coulomb impurity: low-energy universality and discrete scale invariance. Phys. Rev. B 90, 165414 (2014).

  28. 28.

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

  29. 29.

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

  30. 30.

    et al. Local and global screening properties of graphene revealed through Landau level spectroscopy. Preprint at (2015).

  31. 31.

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

  32. 32.

    , & Scanning tunneling spectroscopy of graphene on graphite. Phys. Rev. Lett. 102, 176804 (2009).

Download references

Acknowledgements

Funding was provided by DOE-FG02-99ER45742 (STM/STS), NSF DMR 1207108 (fabrication and characterization). Theoretical work supported by ESF-EUROCORES- EuroGRAPHENE, FWO-VI and Methusalem programme of the Flemish government. We thank V. F. Libisch, M. Pereira and E. Rossi for useful discussions.

Author information

Author notes

    • Jinhai Mao
    •  & Yuhang Jiang

    These authors contributed equally to this work.

Affiliations

  1. Rutgers University, Department of Physics and Astronomy, 136 Frelinghuysen Road, Piscataway, New Jersey 08855, USA

    • Jinhai Mao
    • , Yuhang Jiang
    • , Guohong Li
    •  & Eva Y. Andrei
  2. Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium

    • Dean Moldovan
    • , Massoud Ramezani Masir
    •  & Francois M. Peeters
  3. Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan

    • Kenji Watanabe
    •  & Takashi Taniguchi
  4. Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA

    • Massoud Ramezani Masir

Authors

  1. Search for Jinhai Mao in:

  2. Search for Yuhang Jiang in:

  3. Search for Dean Moldovan in:

  4. Search for Guohong Li in:

  5. Search for Kenji Watanabe in:

  6. Search for Takashi Taniguchi in:

  7. Search for Massoud Ramezani Masir in:

  8. Search for Francois M. Peeters in:

  9. Search for Eva Y. Andrei in:

Contributions

J.M. and Y.J. collected and analysed data and wrote the paper; G.L. built the STM and analysed the data; D.M., M.R.M. and F.M.P. carried out the theoretical work; K.W. and T.T. provided the BN sample. E.Y.A. directed the project, analysed the data and wrote the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Eva Y. Andrei.

Supplementary information

PDF files

  1. 1.

    Supplementary information

    Supplementary information

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nphys3665

Further reading Further reading