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Layer-dependent correlated phases in WSe2/MoS2 moiré superlattice

Nature Materials volume 22, pages 605–611 (2023)Cite this article

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Abstract

Electron correlation plays an essential role in the macroscopic quantum phenomena in the moiré heterostructure, such as antiferromagnetism and correlated insulating phases. Unlike the phenomena where the interaction involves only electrons in one layer, the interaction of distinct phases in two or more layers represents a new horizon forward, such as the one in the Kondo lattice model. Here, using interlayer excitons as a probe, we show that the interlayer interactions in heterobilayers of tungsten diselenide and molybdenum disulfide (WSe2/MoS2) can be electrically switched on and off, resulting in a layer-dependent correlated phase diagram, including single-layer, layer-selective, excitonic-insulator and layer-hybridized regions. We demonstrate that these correlated phases affect the interlayer exciton non-radiative decay pathways. These results reveal the role of strong correlation on interlayer exciton dynamics and pave the way for studying the layer-resolved strong correlation behaviour in moiré heterostructures.

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Fig. 1: Layer-dependent correlated phase, device structure and characterization.
Fig. 2: Gate dependence of IX PL intensity and lifetime.
Fig. 3: Temperature dependence of gate-enhanced intensity and lifetime.
Fig. 4: Theoretical model.

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Data availability

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

References

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

    Article  CAS  Google Scholar 

  2. Liu, Y. et al. Van der Waals heterostructures and devices. Nat. Rev. Mater. 1, 16042 (2016).

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  4. Haigh, S. J. et al. Cross-sectional imaging of individual layers and buried interfaces of graphene-based heterostructures and superlattices. Nat. Mater. 11, 764–767 (2012).

    Article  CAS  Google Scholar 

  5. Ren, H., Wan, Z. & Duan, X. Van der Waals superlattices. Natl Sci. Rev. 9, nwab166 (2021).

  6. Žutić, I., Matos-Abiague, A., Scharf, B., Dery, H. & Belashchenko, K. Proximitized materials. Mater. Today 22, 85–107 (2019).

    Article  Google Scholar 

  7. Xue, J. et al. Scanning tunnelling microscopy and spectroscopy of ultra-flat graphene on hexagonal boron nitride. Nat. Mater. 10, 282–285 (2011).

    Article  CAS  Google Scholar 

  8. Zhang, C. et al. Interlayer couplings, moiré patterns, and 2D electronic superlattices in MoS2/WSe2 hetero-bilayers. Sci. Adv. 3, e1601459 (2017).

    Article  Google Scholar 

  9. He, F. et al. Moiré patterns in 2D materials: a review. ACS Nano 15, 5944–5958 (2021).

    Article  CAS  Google Scholar 

  10. Jin, C. et al. Ultrafast dynamics in van der Waals heterostructures. Nat. Nanotechnol. 13, 994–1003 (2018).

    Article  CAS  Google Scholar 

  11. Zhang, Z. et al. Flat bands in twisted bilayer transition metal dichalcogenides. Nat. Phys. 16, 1093–1096 (2020).

    Article  CAS  Google Scholar 

  12. Pan, Y. et al. Quantum-confined electronic states arising from the moiré pattern of MoS2–WSe2 heterobilayers. Nano Lett. 18, 1849–1855 (2018).

    Article  CAS  Google Scholar 

  13. Wu, F., Lovorn, T., Tutuc, E. & MacDonald, A. H. Hubbard model physics in transition metal dichalcogenide moiré bands. Phys. Rev. Lett. 121, 026402 (2018).

    Article  CAS  Google Scholar 

  14. Li, H. et al. Imaging moiré flat bands in three-dimensional reconstructed WSe2/WS2 superlattices. Nat. Mater. 20, 945–950 (2021).

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  16. Lau, C. N., Bockrath, M. W., Mak, K. F. & Zhang, F. Reproducibility in the fabrication and physics of moiré materials. Nature 602, 41–50 (2022).

    Article  CAS  Google Scholar 

  17. Tang, Y. et al. Simulation of Hubbard model physics in WSe2/WS2 moiré superlattices. Nature 579, 353–358 (2020).

    Article  CAS  Google Scholar 

  18. Xu, Y. et al. Correlated insulating states at fractional fillings of moiré superlattices. Nature 587, 214–218 (2020).

    Article  CAS  Google Scholar 

  19. Regan, E. C. et al. Mott and generalized Wigner crystal states in WSe2/WS2 moiré superlattices. Nature 579, 359–363 (2020).

    Article  CAS  Google Scholar 

  20. Wang, L. et al. Correlated electronic phases in twisted bilayer transition metal dichalcogenides. Nat. Mater. 19, 861–866 (2020).

    Article  CAS  Google Scholar 

  21. Chu, Z. et al. Nanoscale conductivity imaging of correlated electronic states in WSe2/WS2 moiré superlattices. Phys. Rev. Lett. 125, 186803 (2020).

    Article  CAS  Google Scholar 

  22. Huang, X. et al. Correlated insulating states at fractional fillings of the WS2/WSe2 moiré lattice. Nat. Phys. 17, 715–719 (2021).

    Article  CAS  Google Scholar 

  23. Li, T. et al. Charge-order-enhanced capacitance in semiconductor moiré superlattices. Nat. Nanotechnol. 16, 1068–1072 (2021).

    Article  CAS  Google Scholar 

  24. Miao, S. et al. Strong interaction between interlayer excitons and correlated electrons in WSe2/WS2 moiré superlattice. Nat. Commun. 12, 3608 (2021).

    Article  CAS  Google Scholar 

  25. Liu, E. et al. Excitonic and valley-polarization signatures of fractional correlated electronic phases in a WSe2/WS2 moiré superlattice. Phys. Rev. Lett. 127, 037402 (2021).

    Article  CAS  Google Scholar 

  26. Jin, C. et al. Stripe phases in WSe2/WS2 moiré superlattices. Nat. Mater. 20, 940–944 (2021).

    Article  CAS  Google Scholar 

  27. Li, T. et al. Continuous Mott transition in semiconductor moiré superlattices. Nature 597, 350–354 (2021).

    Article  CAS  Google Scholar 

  28. Ghiotto, A. et al. Quantum criticality in twisted transition metal dichalcogenides. Nature 597, 345–349 (2021).

    Article  CAS  Google Scholar 

  29. Li, T. et al. Quantum anomalous Hall effect from intertwined moiré bands. Nature 600, 641–646 (2021).

    Article  CAS  Google Scholar 

  30. Gu, J. et al. Dipolar excitonic insulator in a moiré lattice. Nat. Phys. 18, 395–400 (2022).

  31. Zhang, Z. et al. Correlated interlayer exciton insulator in heterostructures of monolayer WSe2 and moiré WS2/WSe2. Nat. Phys. 18, 1214–1220 (2022).

    Article  CAS  Google Scholar 

  32. Xu, Y. et al. A tunable bilayer Hubbard model in twisted WSe2. Nat. Nanotechnol. 17, 934–939 (2022).

    Article  CAS  Google Scholar 

  33. Dalal, A. & Ruhman, J. Orbitally selective Mott phase in electron-doped twisted transition metal-dichalcogenides: a possible realization of the Kondo lattice model. Phys. Rev. Res. 3, 043173 (2021).

    Article  CAS  Google Scholar 

  34. Kondo, J. Resistance minimum in dilute magnetic alloys. Prog. Theor. Phys. 32, 37–49 (1964).

    Article  CAS  Google Scholar 

  35. Kumar, A., Hu, N. C., MacDonald, A. H. & Potter, A. C. Gate-tunable heavy fermion quantum criticality in a moiré Kondo lattice. Phys. Rev. B 106, L041116 (2022).

    Article  CAS  Google Scholar 

  36. Baek, H. et al. Optical read-out of Coulomb staircases in a moiré superlattice via trapped interlayer trions. Nat. Nanotechnol. 16, 1237–1243 (2021).

    Article  CAS  Google Scholar 

  37. Shimazaki, Y. et al. Strongly correlated electrons and hybrid excitons in a moiré heterostructure. Nature 580, 472–477 (2020).

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  39. Yu, H., Liu, G.-B., Tang, J., Xu, X. & Yao, W. Moiré excitons: from programmable quantum emitter arrays to spin-orbit–coupled artificial lattices. Sci. Adv. 3, e1701696 (2017).

    Article  Google Scholar 

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

    Article  CAS  Google Scholar 

  41. Karni, O. et al. Structure of the moiré exciton captured by imaging its electron and hole. Nature 603, 247–252 (2022).

    Article  CAS  Google Scholar 

  42. Tan, Q. et al. Layer-engineered interlayer excitons. Sci. Adv. 7, eabh0863 (2021).

    Article  CAS  Google Scholar 

  43. Karni, O. et al. Infrared interlayer exciton emission in MoS2/WSe2 heterostructures. Phys. Rev. Lett. 123, 247402 (2019).

    Article  CAS  Google Scholar 

  44. Kim, K. et al. Tunable moiré bands and strong correlations in small-twist-angle bilayer graphene. Proc. Natl Acad. Sci. USA 114, 3364–3369 (2017).

    Article  CAS  Google Scholar 

  45. Choi, J. et al. Twist angle-dependent interlayer exciton lifetimes in van der Waals heterostructures. Phys. Rev. Lett. 126, 047401 (2021).

    Article  CAS  Google Scholar 

  46. Kim, J. et al. Observation of ultralong valley lifetime in WSe2/MoS2 heterostructures. Sci. Adv. 3, e1700518 (2017).

    Article  Google Scholar 

  47. Jauregui, L. A. et al. Electrical control of interlayer exciton dynamics in atomically thin heterostructures. Science 366, 870–875 (2019).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

This work is supported by the Singapore National Research Foundation and A*STAR through their Competitive Research Program (award no. NRF-CRP22-2019-0004, award no. NRF-CRP23-2019-0002 and the Quantum Engineering Programme) and by the Singapore Ministry of Education (MOE2016-T3-1-006 (S)).

Author information

Author notes

  1. These authors contributed equally: Qinghai Tan, Abdullah Rasmita.

Authors and Affiliations

  1. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore

    Qinghai Tan, Abdullah Rasmita, Zhaowei Zhang, Hongbing Cai, Xiangbin Cai, Xuran Dai & Weibo Gao

  2. The Photonics Institute and Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore, Singapore

    Qinghai Tan, Hongbing Cai & Weibo Gao

  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. Department of Physics, The University of Texas at Austin, Austin, TX, USA

    Allan H. MacDonald

  6. Centre for Quantum Technologies, National University of Singapore, Singapore, Singapore

    Weibo Gao

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Contributions

Q.T. fabricated the devices and performed the optical measurement with the help of Z.Z. and H.C.; X.C. performed the electron diffraction and STEM measurement; K.W. and T.T. provided the high-quality BN; A.R. performed the theoretical analysis with the help of X.D. and A.H.M.; and A.R. and Q.T. analysed the data. A.R., Q.T., A.H.M. and W.G. wrote the manuscript with input from all authors. A.H.M. and W.G. supervised the project. All authors contributed to the discussion of the results.

Corresponding authors

Correspondence to Allan H. MacDonald or Weibo Gao.

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Nature Materials thanks Wang Yao and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Gate dependence of IX PL spectra.

Here the colour bar is the intensity. (a) PL spectra as a function of VG. The spectral jump at integer filling factors indicates the gap opening due to electron-electron correlation. (b) PL spectra as a function of . The IX energy experience Stark shift due to the out-of-plane electric field. The estimated interlayer distance is ~0.69 nm, agreeable with the previous reports8,43,47.

Extended Data Fig. 2 Steady-state interlayer exciton PL intensity vs bottom and top gate voltage from two positions in a 1L-WSe2/1L-MoS2 sample at temperature 5 K.

The distance between (a) Location 1 and (b) Location 2 is more than 1 μm.VE.

Extended Data Fig. 3 Gate dependence of IX integrated PL intensity in 1 L/1 L heterostructure.

The intensity is obtained by integrating the time-resolved PL.

Extended Data Fig. 4 Gate dependence of IX PL intensity and lifetime in 1 L/2 L heterostructure.

(a) Steady-state PL intensity vs bottom and top gate voltage at temperature 5 K. PL intensity value peaks at insulating phases with integer filling factor. The peak intensity paths do not follow straight lines. (b) Gate-dependent time-resolved PL. The label shows the VG values. Here, VE = 0V is used. (c) Lifetime vs bottom and top gate voltage. Compared to (a), there is a strong correspondence between PL lifetime and intensity. (d) VG and (e) VE dependent lifetime and integrated PL intensity. The strong correspondence between lifetime and intensity is also observed when the intensity is obtained by integrating the time-resolved PL. Peaks are observed at integer filling factors (labelled in (d)). The gate dependence of the 1 L/2 L heterostructure IX PL spectrum is given in Supplementary Fig. 7.

Extended Data Fig. 5 Gate dependence of IX PL intensity and lifetime in 1 L/3 L heterostructure.

(a) Steady-state PL intensity vs bottom and top gate voltage at temperature 5 K. PL intensity value peaks at insulating phases with integer filling factor. The peak intensity paths do not follow straight lines. (b) Gate-dependent time-resolved PL. The label shows the VG values. Here, VE = 0V is used. (c) Lifetime vs bottom and top gate voltage. Compared to (a), there is a strong correspondence between PL lifetime and intensity. (d) VG and (e) VE dependent lifetime and integrated PL intensity. The strong correspondence between lifetime and intensity is also observed when the intensity is obtained by integrating the time-resolved PL. Peaks are observed at integer filling factors (labelled in (d)). The gate dependence of the 1 L/3 L heterostructure IX PL spectrum is given in Supplementary Fig. 8.

Extended Data Fig. 6 Gate dependence of IX PL intensity and lifetime in another 1 L/1 L sample (Device 2).

(a) Gate-dependent time-resolved PL. The label shows the VG values. Here, VE = 0V is used. (b) VG and (c) VE dependent lifetime and integrated PL intensity. The strong correspondence between lifetime and intensity is also observed when the intensity is obtained by integrating the time-resolved PL.

Supplementary information

Supplementary Information

Supplementary Figs. 1–16 and Notes 1–6.

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Tan, Q., Rasmita, A., Zhang, Z. et al. Layer-dependent correlated phases in WSe2/MoS2 moiré superlattice. Nat. Mater. 22, 605–611 (2023). https://doi.org/10.1038/s41563-023-01521-4

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