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Spectroscopic signatures of many-body correlations in magic-angle twisted bilayer graphene

Author

Listed:
  • Yonglong Xie

    (Princeton University)

  • Biao Lian

    (Princeton University)

  • Berthold Jäck

    (Princeton University)

  • Xiaomeng Liu

    (Princeton University)

  • Cheng-Li Chiu

    (Princeton University)

  • Kenji Watanabe

    (National Institute for Material Science)

  • Takashi Taniguchi

    (National Institute for Material Science)

  • B. Andrei Bernevig

    (Princeton University)

  • Ali Yazdani

    (Princeton University)

Abstract

The discovery of superconducting and insulating states in magic-angle twisted bilayer graphene (MATBG)1,2 has ignited considerable interest in understanding the nature of electronic interactions in this chemically pristine material. The transport properties of MATBG as a function of doping are similar to those of high-transition-temperature copper oxides and other unconventional superconductors1–3, which suggests that MATBG may be a highly interacting system. However, to our knowledge, there is no direct experimental evidence of strong many-body correlations in MATBG. Here we present high-resolution spectroscopic measurements, obtained using a scanning tunnelling microscope, that provide such evidence as a function of carrier density. MATBG displays unusual spectroscopic characteristics that can be attributed to electron–electron interactions over a wide range of doping levels, including those at which superconductivity emerges in this system. We show that our measurements cannot be explained with a mean-field approach for modelling electron–electron interactions in MATBG. The breakdown of a mean-field approach when applied to other correlated superconductors, such as copper oxides, has long inspired the study of the highly correlated Hubbard model3. We show that a phenomenological extended-Hubbard-model cluster calculation, which is motivated by the nearly localized nature of the relevant electronic states of MATBG, produces spectroscopic features that are similar to those that we observed experimentally. Our findings demonstrate the critical role of many-body correlations in understanding the properties of MATBG.

Suggested Citation

  • Yonglong Xie & Biao Lian & Berthold Jäck & Xiaomeng Liu & Cheng-Li Chiu & Kenji Watanabe & Takashi Taniguchi & B. Andrei Bernevig & Ali Yazdani, 2019. "Spectroscopic signatures of many-body correlations in magic-angle twisted bilayer graphene," Nature, Nature, vol. 572(7767), pages 101-105, August.
  • Handle: RePEc:nat:nature:v:572:y:2019:i:7767:d:10.1038_s41586-019-1422-x
    DOI: 10.1038/s41586-019-1422-x
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    Citations

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    Cited by:

    1. Yu-Bo Liu & Jing Zhou & Congjun Wu & Fan Yang, 2023. "Charge-4e superconductivity and chiral metal in 45°-twisted bilayer cuprates and related bilayers," Nature Communications, Nature, vol. 14(1), pages 1-8, December.
    2. Anushree Datta & M. J. Calderón & A. Camjayi & E. Bascones, 2023. "Heavy quasiparticles and cascades without symmetry breaking in twisted bilayer graphene," Nature Communications, Nature, vol. 14(1), pages 1-8, December.
    3. Dongfei Wang & De-Liang Bao & Qi Zheng & Chang-Tian Wang & Shiyong Wang & Peng Fan & Shantanu Mishra & Lei Tao & Yao Xiao & Li Huang & Xinliang Feng & Klaus Müllen & Yu-Yang Zhang & Roman Fasel & Pasc, 2023. "Twisted bilayer zigzag-graphene nanoribbon junctions with tunable edge states," Nature Communications, Nature, vol. 14(1), pages 1-9, December.
    4. J. González & T. Stauber, 2023. "Ising superconductivity induced from spin-selective valley symmetry breaking in twisted trilayer graphene," Nature Communications, Nature, vol. 14(1), pages 1-7, December.
    5. Keshav Singh & Aaron Chew & Jonah Herzog-Arbeitman & B. Andrei Bernevig & Oskar Vafek, 2024. "Topological heavy fermions in magnetic field," Nature Communications, Nature, vol. 15(1), pages 1-12, December.
    6. Hiroki Nakai & Chisa Hotta, 2022. "Perfect flat band with chirality and charge ordering out of strong spin-orbit interaction," Nature Communications, Nature, vol. 13(1), pages 1-9, December.
    7. Si-yu Li & Zhengwen Wang & Yucheng Xue & Yingbo Wang & Shihao Zhang & Jianpeng Liu & Zheng Zhu & Kenji Watanabe & Takashi Taniguchi & Hong-jun Gao & Yuhang Jiang & Jinhai Mao, 2022. "Imaging topological and correlated insulating states in twisted monolayer-bilayer graphene," Nature Communications, Nature, vol. 13(1), pages 1-7, December.

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