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Evidence of a gate-tunable Mott insulator in a trilayer graphene moiré superlattice


The Mott insulator is a central concept in strongly correlated physics and manifests when the repulsive Coulomb interaction between electrons dominates over their kinetic energy1,2. Doping additional carriers into a Mott insulator can give rise to other correlated phenomena such as unusual magnetism and even high-temperature superconductivity2,3. A tunable Mott insulator, where the competition between the Coulomb interaction and the kinetic energy can be varied in situ, can provide an invaluable model system for the study of Mott physics. Here we report the possible realization of such a tunable Mott insulator in a trilayer graphene heterostructure with a moiré superlattice. The combination of the cubic energy dispersion in ABC-stacked trilayer graphene4,5,6,7,8 and the narrow electronic minibands induced by the moiré potential9,10,11,12,13,14,15 leads to the observation of insulating states at the predicted band fillings for the Mott insulator. Moreover, the insulating states in the heterostructure can be tuned: the bandgap can be modulated by a vertical electrical field, and at the same time the electron doping can be modified by a gate to fill the band from one insulating state to another. This opens up exciting opportunities to explore strongly correlated phenomena in two-dimensional moiré superlattice heterostructures.

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Fig. 1: ABC-TLG/hBN moiré superlattice and dual gate FET.
Fig. 2: Transport of gate-tunable Mott state.
Fig. 3: Temperature-dependent resistivity.
Fig. 4: Single-particle band structure of ABC-TLG/hBN moiré superlattice.

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Data availability

The data that support the findings of this study are available from the corresponding authors upon reasonable request.


  1. Mott, N. F. The basis of the electron theory of metals, with special reference to the transition metals. Proc. Phys. Soc. Lond. A 62, 416–422 (1949).

    Article  ADS  Google Scholar 

  2. Imada, M., Fujimori, A. & Tokura, Y. Metal–insulator transitions. Rev. Mod. Phys. 70, 1039–1263 (1998).

    Article  ADS  Google Scholar 

  3. Lee, P. A., Nagaosa, N. & Wen, X. G. Doping a Mott insulator: physics of high-temperature superconductivity. Rev. Mod. Phys. 78, 17–85 (2006).

    Article  ADS  Google Scholar 

  4. Koshino, M. & McCann, E. Trigonal warping and Berry’s phase in ABC-stacked multilayer graphene. Phys. Rev. B 80, 165409 (2009).

    Article  ADS  Google Scholar 

  5. Zhang, F., Sahu, B., Min, H. K. & Macdonald, A. H. Band structure of ABC-stacked graphene trilayers. Phys. Rev. B 82, 035409 (2010).

    Article  ADS  Google Scholar 

  6. Bao, W. et al. Stacking-dependent band gap and quantum transport in trilayer graphene. Nat. Phys. 7, 948–952 (2011).

    Article  Google Scholar 

  7. Lui, C. H., Li, Z. Q., Mak, K. F., Cappelluti, E. & Heinz, T. F. Observation of an electrically tunable band gap in trilayer graphene. Nat. Phys. 7, 944–947 (2011).

    Article  Google Scholar 

  8. Zhang, L. Y., Zhang, Y., Camacho, J., Khodas, M. & Zaliznyak, I. The experimental observation of quantum Hall effect of l = 3 chiral quasiparticles in trilayer graphene. Nat. Phys. 7, 953–957 (2011).

    Article  Google Scholar 

  9. Yankowitz, M. et al. Emergence of superlattice Dirac points in graphene on hexagonal boron nitride. Nat. Phys. 8, 382–386 (2012).

    Article  Google Scholar 

  10. Dean, C. R. et al. Hofstadter’s butterfly and the fractal quantum Hall effect in moiré superlattices. Nature 497, 598–602 (2013).

    Article  ADS  Google Scholar 

  11. Hunt, B. et al. Massive Dirac fermions and Hofstadter butterfly in a van der Waals heterostructure. Science 340, 1427–1430 (2013).

    Article  ADS  Google Scholar 

  12. Ponomarenko, L. A. et al. Cloning of Dirac fermions in graphene superlattices. Nature 497, 594–597 (2013).

    Article  ADS  Google Scholar 

  13. Wallbank, J. R., Patel, A. A., Mucha-Kruczynski, M., Geim, A. K. & Falko, V. I. Generic miniband structure of graphene on a hexagonal substrate. Phys. Rev. B 87, 245408 (2013).

    Article  ADS  Google Scholar 

  14. Jung, J., Raoux, A., Qiao, Z. & MacDonald, A. H. Ab initio theory of moiré superlattice bands in layered two dimensional materials. Phys. Rev. B 89, 205414 (2014).

    Article  ADS  Google Scholar 

  15. Jung, J., DaSilva, A. M., MacDonald, A. H. & Adam, S. A. Origin of band gaps in graphene on hexagonal boron nitride. Nat. Commun. 6, 6308 (2015).

    Article  ADS  Google Scholar 

  16. Geim, A. K. & Grigorieva, I. V. Van der Waals heterostructures. Nature 499, 419–425 (2013).

    Article  Google Scholar 

  17. Yang, W. et al. Epitaxial growth of single-domain graphene on hexagonal boron nitride. Nat. Mater. 12, 792–797 (2013).

    Article  ADS  Google Scholar 

  18. Shi, Z. et al. Gate-dependent pseudospin mixing in graphene/boron nitride moiré superlattices. Nat. Phys. 10, 743–747 (2014).

    Article  Google Scholar 

  19. Mak, K. F., Lee, C., Hone, J., Shan, J. & Heinz, T. F. Atomically thin MoS2: a new direct-gap semiconductor. Phys. Rev. Lett. 105, 136805 (2010).

    Article  ADS  Google Scholar 

  20. Splendiani, A. et al. Emerging photoluminescence in monolayer MoS2. Nano. Lett. 10, 1271–1275 (2010).

    Article  ADS  Google Scholar 

  21. Rivera, P. et al. Valley-polarized exciton dynamics in a 2D semiconductor heterostructure. Science 351, 688–691 (2016).

    Article  ADS  MathSciNet  Google Scholar 

  22. Yu, H. Y., Wang, Y., Tong, Q. J., Xu, X. D. & Yao, W. Anomalous light cones and valley optical selection rules of interlayer excitons in twisted heterobilayers. Phys. Rev. Lett. 115, 187002 (2015).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  24. Novoselov, K. S. et al. Two-dimensional gas of massless Dirac fermions in graphene. Nature 438, 197–200 (2005).

    Article  ADS  Google Scholar 

  25. Zhang, Y. B., Tan, Y. W., Stormer, H. L. & Kim, P. Experimental observation of the quantum Hall effect and Berry’s phase in graphene. Nature 438, 201–204 (2005).

    Article  ADS  Google Scholar 

  26. Lee, Y. et al. Competition between spontaneous symmetry breaking and single-particle gaps in trilayer graphene. Nat. Commun. 5, 5656 (2014).

    Article  Google Scholar 

  27. Ju, L. et al. Topological valley transport at bilayer graphene domain walls. Nature 520, 650–655 (2015).

    Article  ADS  Google Scholar 

  28. Zhang, Y. B. et al. Direct observation of a widely tunable bandgap in bilayer graphene. Nature 459, 820–823 (2009).

    Article  ADS  Google Scholar 

  29. Hubbard, J. Electron correlations in narrow energy bands. Proc. R. Soc. Lond. A 276, 238–257 (1963).

    Article  ADS  Google Scholar 

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The authors thank C. Jin, E. Regan, X. Lu, Y. Shan, S. Wu and G. Zhang for discussions and help with sample preparation. The trilayer graphene sample fabrication and experimental study was supported by the Office of Naval Research (award no. N00014-15-1-2651). The initial idea and proof-of-principle calculation of 2D flatband engineering was supported by an ARO MURI award (W911NF-15-1-0447). Part of the sample fabrication was conducted at the Nano-fabrication Laboratory at Fudan University. B.L.C. was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2018R1A6A1A06024977) and by grants NRF-2016R1A2B4010105 and NRF-2017R1D1A1B03035932. J.J. was supported by the Samsung Science and Technology Foundation under project no. SSTF-BA1802-06. Y.Z. acknowledges financial support from the National Key Research Program of China (grant nos. 2016YFA0300703 and 2018YFA0305600), the NSF of China (grant nos. U1732274, 11527805, 11425415 and 11421404), Shanghai Municipal Science and Technology Commission (grant no. 18JC1410300) and the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDB30000000). Z.S. is supported by the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning and the National Natural Science Foundation of China under grant no. 11574204. B.L., H.L. and Z.S. are supported by the National Key Research and Development Program of China (grant 2016YFA0302001) and National Natural Science Foundation of China (grants 11574204, 11774224). Growth of hBN crystals was supported by the Elemental Strategy Initiative conducted by the MEXT, Japan and JSPS KAKENHI grant no. JP15K21722. Part of the sample fabrication was conducted at Fudan Nano-fabrication Lab.

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Authors and Affiliations



F.W. and Y.Z. supervised the project. G.C. fabricated samples and performed transport measurements. G.C., L.J., S.W., B.L., H.L. and Z.S. prepared trilayer graphene and performed near-field infrared and atomic force microscopy measurements. B.L.C. and J.J. calculated the band structures. K.W. and T.T. grew hBN single crystals. G.C., Y.Z. and F.W. analysed the data.

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Correspondence to Yuanbo Zhang or Feng Wang.

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Extended Data

Extended data figures 1–7; references 30–35

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Chen, G., Jiang, L., Wu, S. et al. Evidence of a gate-tunable Mott insulator in a trilayer graphene moiré superlattice. Nat. Phys. 15, 237–241 (2019).

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