Correlated electronic phases in twisted bilayer transition metal dichalcogenides

Abstract

In narrow electron bands in which the Coulomb interaction energy becomes comparable to the bandwidth, interactions can drive new quantum phases. Such flat bands in twisted graphene-based systems result in correlated insulator, superconducting and topological states. Here we report evidence of low-energy flat bands in twisted bilayer WSe2, with signatures of collective phases observed over twist angles that range from 4 to 5.1°. At half-band filling, a correlated insulator appeared that is tunable with both twist angle and displacement field. At a 5.1° twist, zero-resistance pockets were observed on doping away from half filling at temperatures below 3 K, which indicates a possible transition to a superconducting state. The observation of tunable collective phases in a simple band, which hosts only two holes per unit cell at full filling, establishes twisted bilayer transition metal dichalcogenides as an ideal platform to study correlated physics in two dimensions on a triangular lattice.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Flat bands in twisted bilayer WSe2.
Fig. 2: Displacement-field dependence of vHS for 4.5° tWSe2.
Fig. 3: Angle and displacement-field dependence of the correlated insulator.
Fig. 4: Observation of zero resistance regions around half filling.

Data availability

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

References

  1. 1.

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

    CAS  Article  Google Scholar 

  2. 2.

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

    CAS  Article  Google Scholar 

  3. 3.

    Park, C.-H., Yang, L. I., Son, Y.-W., Cohen, M. L. & Louie, S. G. Anisotropic behaviours of massless Dirac fermions in graphene under periodic potentials. Nat. Phys. 4, 213–217 (2008).

    CAS  Article  Google Scholar 

  4. 4.

    Bistritzer, R. & MacDonald, A. H. Moiré bands in twisted double-layer graphene. Proc. Natl Acad. Sci. USA 108, 12233–12237 (2011).

    CAS  Article  Google Scholar 

  5. 5.

    SuárezMorell, E., Correa, J. D., Vargas, P., Pacheco, M. & Barticevic, Z. Flat bands in slightly twisted bilayer graphene: tight-binding calculations. Phys. Rev. B 82, 121407 (2010).

    Article  Google Scholar 

  6. 6.

    Cao, Y. et al. Unconventional superconductivity in magic-angle graphene superlattices. Nature 556, 43–50 (2018).

    CAS  Article  Google Scholar 

  7. 7.

    Cao, Y. et al. Correlated insulator behaviour at half-filling in magic-angle graphene superlattices. Nature 556, 80–84 (2018).

    CAS  Article  Google Scholar 

  8. 8.

    Yankowitz, M. et al. Tuning superconductivity in twisted bilayer graphene. Science 363, 1059–1064 (2019).

    CAS  Article  Google Scholar 

  9. 9.

    Sharpe, A. L. et al. Emergent ferromagnetism near three-quarters filling in twisted bilayer graphene. Science 365, 605–608 (2019).

    CAS  Article  Google Scholar 

  10. 10.

    Lu, X. et al. Superconductors, orbital magnets and correlated states in magic-angle bilayer graphene. Nature 574, 653–657 (2019).

    CAS  Article  Google Scholar 

  11. 11.

    Serlin, M. et al. Intrinsic quantized anomalous Hall effect in a moiré heterostructure. Science 367, 900–903 (2020).

    CAS  Article  Google Scholar 

  12. 12.

    Liu, X. et al. (2019) Spin-polarized correlated insulator and superconductor in twisted double bilayer graphene. Preprint at: http://arxiv.org/abs/1903.08130 (2019).

  13. 13.

    Cao, Yuan, et al. Tunable correlated states and spin-polarized phases in twisted bilayer–bilayer graphene. Nature https://doi.org/10.1038/s41586-020-2260-6 (2020).

  14. 14.

    Shen, C. et al. Correlated states in twisted double bilayer graphene. Nat. Phys. 16, 520–525 (2020).

    CAS  Article  Google Scholar 

  15. 15.

    Burg, G. W. et al. Correlated insulating states in twisted double bilayer graphene. Phys. Rev. Lett. 123, 197702 (2019).

    CAS  Article  Google Scholar 

  16. 16.

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

    CAS  Article  Google Scholar 

  17. 17.

    Chen, G. et al. Signatures of tunable superconductivity in a trilayer graphene moiré superlattice. Nature 572, 215–219 (2019).

    CAS  Article  Google Scholar 

  18. 18.

    Chen, G. et al. Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice. Nature 579, 56–61 (2020).

    CAS  Article  Google Scholar 

  19. 19.

    Wu, F., Lovorn, T., Tutuc, E. & Macdonald, A. H. Hubbard model physics in transition metal dichalcogenide moiré bands. Phys. Rev. Lett. 121, 26402 (2018).

    CAS  Article  Google Scholar 

  20. 20.

    Wu, F., Lovorn, T., Tutuc, E., Martin, I. & Macdonald, A. H. Topological insulators in twisted transition metal dichalcogenide homobilayers. Phys. Rev. Lett. 122, 86402 (2019).

    CAS  Article  Google Scholar 

  21. 21.

    Naik, M. H. & Jain, M. Ultraflatbands and shear solitons in moiré patterns of twisted bilayer transition metal dichalcogenides. Phys. Rev. Lett. 121, 266401 (2018).

    CAS  Article  Google Scholar 

  22. 22.

    Ruiz-Tijerina, D. A. & Fal’Ko, V. I. Interlayer hybridization and moiré superlattice minibands for electrons and excitons in heterobilayers of transition-metal dichalcogenides. Phys. Rev. B 99, 125424 (2019).

    CAS  Article  Google Scholar 

  23. 23.

    Schrade, C. & Fu, L. Spin-valley density wave in moiré materials. Phys. Rev. B 100, 035413 (2019).

    CAS  Article  Google Scholar 

  24. 24.

    Dagotto, E. Correlated electrons in high-temperature superconductors. Rev. Mod. Phys. 66, 763–840 (1994).

    CAS  Article  Google Scholar 

  25. 25.

    Scalapino, D. J. A common thread: the pairing interaction for unconventional superconductors. Rev. Mod. Phys. 84, 1383–1417 (2012).

    CAS  Article  Google Scholar 

  26. 26.

    LeBlanc, J. P. F. et al. Solutions of the two-dimensional Hubbard model: benchmarks and results from a wide range of numerical algorithms. Phys. Rev. X 5, 041041 (2015).

    Google Scholar 

  27. 27.

    Mazurenko, A. et al. A cold-atom Fermi–Hubbard antiferromagnet. Nature 545, 462–466 (2017).

    CAS  Article  Google Scholar 

  28. 28.

    Kim, K. et al. van der Waals heterostructures with high accuracy rotational alignment. Nano Lett. 16, 1989–1995 (2016).

    CAS  Article  Google Scholar 

  29. 29.

    Edelberg, D. et al. Approaching the intrinsic limit in transition metal diselenides via point defect control. Nano Lett. 19, 4371–4379 (2019).

    CAS  Article  Google Scholar 

  30. 30.

    Movva, H. C. P. et al. High-mobility holes in dual-gated WSe2 field-effect transistors. ACS Nano 9, 10402–10410 (2015).

    CAS  Article  Google Scholar 

  31. 31.

    Movva, H. C. P. et al. Density-dependent quantum Hall states and Zeeman splitting in monolayer and bilayer WSe2. Phys. Rev. Lett. 118, 247701 (2017).

    Article  Google Scholar 

  32. 32.

    Laturia, A., Van de Put, M. L. & Vandenberghe, W. G. Dielectric properties of hexagonal boron nitride and transition metal dichalcogenides: from monolayer to bulk. npj 2D Mater. Appl. 2, 6 (2018).

    Article  Google Scholar 

  33. 33.

    Kormányos, A. et al. k.p theory for two-dimensional transition metal dichalcogenide semiconductors. 2D Materials 2, 022001 (2015).

    Article  Google Scholar 

  34. 34.

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

    CAS  Article  Google Scholar 

  35. 35.

    Padhi, B., Setty, C. & Phillips, P. W. Doped twisted bilayer graphene near magic angles: proximity to Wigner crystallization, not Mott insulation. Nano Lett. 18, 6175–6181 (2018).

    CAS  Article  Google Scholar 

Download references

Acknowledgements

Studies of the tunable correlated states in the twisted bilayer WSe2 were supported as part of Programmable Quantum Materials, an Energy Frontier Research Center funded by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under award DE-SC0019443. The synthesis of the WSe2 crystals was supported by the NSF MRSEC programme through Columbia in the Center for Precision Assembly of Superstratic and Superatomic Solids (DMR-1420634). The theoretical work was supported by the European Research Council (ERC-2015-AdG694097), cluster of Excellence AIM, SFB925 and Grupos Consolidados (IT1249-19). The Flatiron Institute is a division of the Simons Foundation. We acknowledge support from the Max Planck–New York Center for Non-Equilibrium Quantum Phenomena. We thank F. Wu and L. Fu for helpful discussions. We also thank O. Stapleton, P. Wu and Z. Zheng for help in the device fabrication.

Author information

Affiliations

Authors

Contributions

L.W., E.-M.S., A.G., C.T. and D.A.R. fabricated the samples. L.W., E.-M.S. and A.G. performed the transport measurements and analysed the data. Y.B. and X.Z. performed the SHG measurements. D.A.R., B.K. and J.H. grew the WSe2 crystals. K.W. and T.T. grew the hBN crystals. L.X. performed the density functional theory and tight-binding calculations. M.C. and D.M.K. did the mean-field calculations. A.R. supervised the theoretical aspects of this work. L.W., E.-M.S., A.G., C.R.D. and A.P. wrote the manuscript with input from all the authors.

Corresponding authors

Correspondence to Angel Rubio or Abhay N. Pasupathy or Cory R. Dean.

Ethics declarations

Competing interests

The authors declare no competing interest.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary information

Supplementary theory calculation and Figs. 1–19.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Wang, L., Shih, E., Ghiotto, A. et al. Correlated electronic phases in twisted bilayer transition metal dichalcogenides. Nat. Mater. 19, 861–866 (2020). https://doi.org/10.1038/s41563-020-0708-6

Download citation

Further reading