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High-resolution tunnelling spectroscopy of fractional quantum Hall states

Nature Physics volume 21, pages 716–723 (2025)Cite this article

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Abstract

Strong interactions between electrons in two-dimensional systems in the presence of a high magnetic field give rise to fractional quantum Hall states that host quasiparticles with a fractional charge and fractional exchange statistics. Here we demonstrate high-resolution scanning tunnelling microscopy and spectroscopy of fractional quantum Hall states in ultra-clean Bernal-stacked bilayer graphene devices. Spectroscopy measurements show sharp excitations that have been predicted to emerge when electrons fractionalize into bound states of quasiparticles. We found energy gaps for candidate non-abelian fractional states that are larger by a factor of five than those in other related systems, for example, semiconductor heterostructures, and this suggests that bilayer graphene is an ideal platform for manipulating these quasiparticles and for creating topological quantum bits. We also found previously unobserved fractional states in our very clean graphene samples.

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Fig. 1: Experimental set-up and tunnelling spectra at zero and low magnetic fields.
Fig. 2: Atomic wavefunction imaging of N = 0 and 1 LLs under B = 10 T.
Fig. 3: FQH states within 0 < ν < 1 in the N = 0 LL.
Fig. 4: FQH states within −1 < ν < 0 in the N = 1 LL.
Fig. 5: FQH states within 4 < ν < 5 in the N = 2 LL.

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Source data are provided with this paper. Other data that supports the findings of this study are available from the corresponding author upon request.

Code availability

The code that supports the findings of this study is available from the corresponding author upon reasonable request.

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Acknowledgements

This work was primarily supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences (Grant No. DE-FG02-07ER46419), the Gordon and Betty Moore Foundation’s EPiQS initiative (Grant No. GBMF9469 to A.Y.). Other support for the experimental work was provided by NSF-MRSEC through the Princeton Center for Complex Materials (Grant Nos. NSF-DMR- 2011750, NSF-DMR-2312311, ARO MURI (W911NF-21-2-0147), ONR N00014-21-1-2592 and ONR N000142412471). A.Y. acknowledges the hospitality of the Aspen Center for Physics, which is supported by the National Science Foundation (Grant No. PHY-1607611), where part of this work was carried out. M.P.Z. and T.W. are supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division (Contract No. DE-AC02-05CH11231), within the van der Waals Heterostructures Program (KCWF16). Z.P. acknowledges support from the Leverhulme Trust Research Leadership Award RL-2019-015 and in part by grant NSF PHY-2309135 to the Kavli Institute for Theoretical Physics. We thank A. Young and A. Yacoby for useful conversations.

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Author notes

  1. These authors contributed equally: Yuwen Hu, Yen-Chen Tsui, Minhao He.

Authors and Affiliations

  1. Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ, USA

    Yuwen Hu, Yen-Chen Tsui, Minhao He, Umut Kamber, Amir S. Mohammadi & Ali Yazdani

  2. Department of Physics, University of California at Berkeley, Berkeley, CA, USA

    Taige Wang & Michael P. Zaletel

  3. Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan

    Kenji Watanabe

  4. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan

    Takashi Taniguchi

  5. School of Physics and Astronomy, University of Leeds, Leeds, UK

    Zlatko Papić

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Contributions

Y.H., Y.-C.T., M.H., U.K. and A.Y. devised the experiments. Y.H., Y.-C.T., M.H., and U.K. created the device structures and carried out the STM measurements and data analysis. A.S.M., T.W., Z.P. and M.P.Z. carried out the theoretical calculations. K.W. and T.T. provided the hBN substrates. Y.H., Y.-C.T., M.H., A.Y., T.W., Z.P. and M.P.Z. all collaborated in writing the manuscript.

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Correspondence to Ali Yazdani.

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Nature Physics thanks David Mross, Miguel Ugeda and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Hu, Y., Tsui, YC., He, M. et al. High-resolution tunnelling spectroscopy of fractional quantum Hall states. Nat. Phys. 21, 716–723 (2025). https://doi.org/10.1038/s41567-025-02830-y

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