Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Tunable crystal symmetry in graphene–boron nitride heterostructures with coexisting moiré superlattices

Abstract

In van der Waals (vdW) heterostructures consisting of atomically thin crystals layered on top of one another, lattice mismatch and rotation between the layers can result in long-wavelength moiré superlattices. These moiré patterns can drive notable band structure reconstruction of the composite material, leading to a wide range of emergent phenomena including superconductivity1,2,3, magnetism4, fractional Chern insulating states5 and moiré excitons6,7,8,9. Here, we investigate devices consisting of monolayer graphene encapsulated between two crystals of boron nitride (BN), in which the rotational alignment of all three components is controlled. We find that bandgaps in the graphene arising from perfect rotational alignment with both BN layers can be modified considerably depending on whether the relative orientation of the two BN layers is 0° or 60°, suggesting a tunable transition between the absence or presence of inversion symmetry in the heterostructure. Small deviations (<1°) from perfect alignment of all three layers leads to coexisting long-wavelength moiré potentials, resulting in a highly reconstructed graphene band structure featuring multiple secondary Dirac points. Our results demonstrate that the interplay between multiple moiré patterns can be utilized to controllably modify the symmetry and electronic properties of the composite heterostructure.

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: Aligning top and bottom BN flakes to graphene.
Fig. 2: Crystal symmetry and room-temperature transport as a function of twist angle.
Fig. 3: Graphene bandgaps as a function of top-BN twist angle in devices with graphene aligned to bottom BN.
Fig. 4: Coexisting moiré structures in BN–graphene–BN heterostructures.

Data availability

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

References

  1. 1.

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

    CAS  Article  Google Scholar 

  2. 2.

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

    CAS  Article  Google Scholar 

  3. 3.

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

    CAS  Article  Google Scholar 

  4. 4.

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

    CAS  Article  Google Scholar 

  5. 5.

    Spanton, E. M. et al. Observation of fractional Chern insulators in a van der Waals heterostructure. Science 260, 62–66 (2018).

    Article  Google Scholar 

  6. 6.

    Seyler, K. L. et al. Signatures of moiré-trapped valley excitons in MoSe2/WSe2 heterobilayers. Nature 567, 66–70 (2019).

    CAS  Article  Google Scholar 

  7. 7.

    Tran, K. et al. Evidence for moiré excitons in van der Waals heterostructures. Nature 567, 71–75 (2019).

    CAS  Article  Google Scholar 

  8. 8.

    Jin, C. et al. Observation of moiré excitons in WSe2/WS2 heterostructure superlattices. Nature 567, 76–80 (2019).

    CAS  Article  Google Scholar 

  9. 9.

    Alexeev, E. M. et al. Resonantly hybridized excitons in moiré superlattices in van der Waals heterostructures. Nature 567, 81–86 (2019).

    CAS  Article  Google Scholar 

  10. 10.

    Yankowitz, M., Ma, Q., Jarillo-Herrero, P. & LeRoy, B. J. van der Waals heterostructures combining graphene and hexagonal boron nitride. Nat. Rev. Phys. 1, 112–125 (2019).

    Article  Google Scholar 

  11. 11.

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

    CAS  Article  Google Scholar 

  12. 12.

    Ribeiro-Palau, R. et al. Twistable electronics with dynamically rotatable heterostructures. Science 361, 690–693 (2018).

    CAS  Article  Google Scholar 

  13. 13.

    Yankowitz, M. et al. Dynamic band-structure tuning of graphene moiré superlattices with pressure. Nature 557, 404–408 (2018).

    CAS  Article  Google Scholar 

  14. 14.

    Forsythe, C. et al. Band structure engineering of 2D materials using patterned dielectric superlattices. Nat. Nanotechnol. 13, 566–571 (2018).

    CAS  Article  Google Scholar 

  15. 15.

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

    CAS  Article  Google Scholar 

  16. 16.

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

    CAS  Article  Google Scholar 

  17. 17.

    Wang, L. et al. New generation of moiré superlattices in doubly aligned hBN/graphene/hBN heterostructures. Nano Lett. 19, 2371–2376 (2019).

    CAS  Article  Google Scholar 

  18. 18.

    Chari, T., Riberio-Palau, R., Dean, C. R. & Shepard, K. Resistivity of rotated graphite–graphene contacts. Nano Lett. 16, 4477–4482 (2016).

    CAS  Article  Google Scholar 

  19. 19.

    Eckmann, A. et al. Raman fingerprint of aligned graphene/h-BN superlattices. Nano Lett. 13, 5242–5246 (2013).

    CAS  Article  Google Scholar 

  20. 20.

    Wang, L. et al. Evidence for a fractional fractal quantum Hall effect in graphene superlattices. Science 350, 1231–1234 (2015).

    CAS  Article  Google Scholar 

  21. 21.

    Woods, C. R. et al. Commensurate–incommensurate transition in graphene on hexagonal boron nitride. Nat. Phys. 10, 451–456 (2014).

    CAS  Article  Google Scholar 

  22. 22.

    Chen, Z.-G. et al. Observation of an intrinsic bandgap and Landau level renormalization in graphene/boron-nitride heterostructures. Nat. Commun. 5, 4461 (2014).

    CAS  Article  Google Scholar 

  23. 23.

    Wang, E. et al. Gaps induced by inversion symmetry breaking and second-generation Dirac cones in graphene/hexagonal boron nitride. Nat. Phys. 12, 1111–1115 (2016).

    CAS  Article  Google Scholar 

  24. 24.

    Song, J. C. W., Shytov, A. V. & Levitov, L. S. Electron interactions and gap opening in graphene superlattices. Phys. Rev. Lett. 111, 266801 (2013).

    Article  Google Scholar 

  25. 25.

    Bokdam, M., Amlaki, T., Brocks, G. & Kelly, P. J. Band gaps in incommensurable graphene on hexagonal boron nitride. Phys. Rev. B 89, 201404(R) (2014).

    Article  Google Scholar 

  26. 26.

    Moon, P. & Koshino, M. Electronic properties of graphene/hexagonal-boron-nitride moiré superlattice. Phys. Rev. B 90, 155406 (2014).

    Article  Google Scholar 

  27. 27.

    Wallbank, J. R., Mucha-Kruczynski, M., Chen, X. & Fal’ko, V. I. Moiré superlattice effects in graphene/boron-nitride van der Waals heterostructures. Ann. Phys. 527, 359–376 (2015).

    CAS  Article  Google Scholar 

  28. 28.

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

    CAS  Article  Google Scholar 

  29. 29.

    San-Jose, P., Gutiérrez-Rubio, A., Sturla, M. & Guinea, F. Spontaneous strains and gap in graphene on boron nitride. Phys. Rev. B 90, 075428 (2014).

    Article  Google Scholar 

  30. 30.

    Slotman, G. et al. Effect of structural relaxation on the electronic structure of graphene on hexagonal boron nitride. Phys. Rev. Lett. 115, 186801 (2015).

    CAS  Article  Google Scholar 

  31. 31.

    Jung, J. et al. Moiré band model and band gaps of graphene on hexagonal boron nitride. Phys. Rev. B 96, 085442 (2017).

    Article  Google Scholar 

  32. 32.

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

    CAS  Article  Google Scholar 

Download references

Acknowledgements

We thank R. Ribeiro-Palau, C. Zhang and S. Chen for technical support, as well as J. Jung, M. Koshino and C. Marianetti for helpful discussions. This work was primarily supported by the NSF MRSEC program through Columbia in the Center for Precision Assembly of Superstratic and Superatomic Solids (DMR-1420634). Sample device design and fabrication was partially supported by DoE Pro-QM EFRC (DE-SC0019443). N.R.F. acknowledges support from the Stewardship Science Graduate Fellowship program provided under cooperative agreement number DE-NA0002135. C.R.D. acknowledges the support of the David and Lucile Packard Foundation. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan and the CREST (JPMJCR15F3), JST.

Author information

Affiliations

Authors

Contributions

N.R.F. and L.M. fabricated the devices. N.R.F. and M.Y. performed the measurements and analysed the data. K.W. and T.T. grew the hBN crystals. C.R.D. and J.H. advised on the experiments. The manuscript was written with input from all authors.

Corresponding authors

Correspondence to Cory R. Dean or James Hone.

Ethics declarations

Competing interests

The authors declare no competing interests.

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 Sections 1–8, Figs. 1–8, Table 1 and refs. 1–8.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Finney, N.R., Yankowitz, M., Muraleetharan, L. et al. Tunable crystal symmetry in graphene–boron nitride heterostructures with coexisting moiré superlattices. Nat. Nanotechnol. 14, 1029–1034 (2019). https://doi.org/10.1038/s41565-019-0547-2

Download citation

Further reading

Search

Quick links

Find nanotechnology articles, nanomaterial data and patents all in one place. Visit Nano by Nature Research