Skip to main content

Thank you for visiting 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.

Identification of spin, valley and moiré quasi-angular momentum of interlayer excitons


Moiré superlattices provide a powerful way to engineer the properties of electrons and excitons in two-dimensional van der Waals heterostructures1,2,3,4,5,6,7,8. The moiré effect can be especially strong for interlayer excitons, where electrons and holes reside in different layers and can be addressed separately. In particular, it was recently proposed that the moiré superlattice potential not only localizes interlayer exciton states at different superlattice positions, but also hosts an emerging moiré quasi-angular momentum (QAM) that periodically switches the optical selection rules for interlayer excitons at different moiré sites9,10. Here, we report the observation of multiple interlayer exciton states coexisting in a WSe2/WS2 moiré superlattice and unambiguously determine their spin, valley and moiré QAM through novel resonant optical pump–probe spectroscopy and photoluminescence excitation spectroscopy. We demonstrate that interlayer excitons localized at different moiré sites can exhibit opposite optical selection rules due to the spatially varying moiré QAM. Our observation reveals new opportunities to engineer interlayer exciton states and valley physics with moiré superlattices for optoelectronic and valleytronic applications.

Your institute does not have access to this article

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Interlayer moiré excitons in near-zero twist angle WSe2/WS2 heterostructure.
Fig. 2: Interlayer moiré excitons probed by helicity-resolved PLE spectroscopy.
Fig. 3: Interlayer moiré excitons probed by resonant pump–probe spectroscopy.

Data availability

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


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

    ADS  Article  Google Scholar 

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

    ADS  Article  Google Scholar 

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

    Article  Google Scholar 

  4. Spanton, E. M. et al. Observation of fractional Chern insulators in a van der Waals heterostructure. Science 360, 62–66 (2018).

    ADS  Article  Google Scholar 

  5. 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).

    ADS  Article  Google Scholar 

  6. Song, J. C. W., Samutpraphoot, P. & Levitov, L. S. Topological Bloch bands in graphene superlattices. Proc. Natl Acad. Sci. USA 112, 10879–10883 (2015).

    ADS  MathSciNet  Article  Google Scholar 

  7. Gorbachev, R. V. et al. Detecting topological currents in graphene superlattices. Science 346, 448–451 (2014).

    ADS  Article  Google Scholar 

  8. Lee, M. et al. Ballistic miniband conduction in a graphene superlattice. Science 353, 1526–1529 (2016).

    ADS  Article  Google Scholar 

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

    ADS  Article  Google Scholar 

  10. Wu, F. C., Lovorn, T. & MacDonald, A. H. Theory of optical absorption by interlayer excitons in transition metal dichalcogenide heterobilayers. Phys. Rev. B 97, 035306 (2018).

    ADS  Article  Google Scholar 

  11. Rivera, P. et al. Observation of long-lived interlayer excitons in monolayer MoSe2–WSe2 heterostructures. Nat. Commun. 6, 6242 (2015).

    ADS  Article  Google Scholar 

  12. Latini, S., Winther, K. T., Olsen, T. & Thygesen, K. S. Interlayer excitons and band alignment in MoS2/hBN/WSe2 van der Waals heterostructures. Nano Lett. 17, 938–945 (2017).

    ADS  Article  Google Scholar 

  13. Hsu, W. T. et al. Negative circular polarization emissions from WSe2/MoSe2 commensurate heterobilayers. Nat. Commun. 9, 1356 (2018).

    ADS  Article  Google Scholar 

  14. Hanbicki, A. T. et al. Double indirect interlayer exciton in a MoSe2/WSe2 van der Waals heterostructure. ACS Nano 12, 4719–4726 (2018).

    Article  Google Scholar 

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

    ADS  Article  Google Scholar 

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

    ADS  Article  Google Scholar 

  17. Ciarrocchi, A. et al. Polarization switching and electrical control of interlayer excitons in two-dimensional van der Waals heterostructures. Nat. Photon. 13, 131–136 (2019).

    ADS  Article  Google Scholar 

  18. Ross, J. S. et al. Interlayer exciton optoelectronics in a 2D heterostructure p–n junction. Nano Lett. 17, 638–643 (2017).

    ADS  Article  Google Scholar 

  19. Gillen, R. & Maultzsch, J. Interlayer excitons in MoSe2/WSe2 heterostructures from first principles. Phys. Rev. B 97, 165306 (2018).

    ADS  Article  Google Scholar 

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

    ADS  Article  Google Scholar 

  21. Wu, F. C., Lovorn, T. & MacDonald, A. H. Topological exciton bands in moire heterojunctions. Phys. Rev. Lett. 118, 147401 (2017).

    ADS  Article  Google Scholar 

  22. Zhang, N. et al. Moiré intralayer excitons in a MoSe2/MoS2 heterostructure. Nano Lett. 18, 7651–7657 (2018).

    ADS  Article  Google Scholar 

  23. Cao, T. et al. Valley-selective circular dichroism of monolayer molybdenum disulphide. Nat. Commun. 3, 887 (2012).

    ADS  Article  Google Scholar 

  24. Mak, K. F., He, K., Shan, J. & Heinz, T. F. Control of valley polarization in monolayer MoS2 by optical helicity. Nat. Nanotechnol. 7, 494–498 (2012).

    ADS  Article  Google Scholar 

  25. Xiao, D., Liu, G.-B., Feng, W., Xu, X. & Yao, W. Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides. Phys. Rev. Lett. 108, 196802 (2012).

    ADS  Article  Google Scholar 

  26. Andor, K. et al. k·p theory for two-dimensional transition metal dichalcogenide semiconductors. 2D Mater. 2, 022001 (2015).

    Article  Google Scholar 

  27. Zhang, X.-X., You, Y., Zhao, S. Y. F. & Heinz, T. F. Experimental evidence for dark excitons in monolayer WSe2. Phys. Rev. Lett. 115, 257403 (2015).

    ADS  Article  Google Scholar 

  28. Wang, G. et al. In-plane propagation of light in transition metal dichalcogenide monolayers: optical selection rules. Phys. Rev. Lett. 119, 047401 (2017).

    ADS  Article  Google Scholar 

  29. Echeverry, J. P., Urbaszek, B., Amand, T., Marie, X. & Gerber, I. C. Splitting between bright and dark excitons in transition metal dichalcogenide monolayers. Phys. Rev. B 93, 121107 (2016).

    ADS  Article  Google Scholar 

  30. Zhou, Y. et al. Probing dark excitons in atomically thin semiconductors via near-field coupling to surface plasmon polaritons. Nat. Nanotechnol. 12, 856–860 (2017).

    ADS  Article  Google Scholar 

  31. Li, Z. P. et al. Revealing the biexciton and trion-exciton complexes in BN encapsulated WSe2. Nat. Commun. 9, 3719 (2018).

    ADS  Article  Google Scholar 

  32. Chen, S. Y., Goldstein, T., Taniguchi, T., Watanabe, K. & Yan, J. Coulomb-bound four- and five-particle intervalley states in an atomically-thin semiconductor. Nat. Commun. 9, 3717 (2018).

    ADS  Article  Google Scholar 

  33. Yu, H. Y., Liu, G. B. & Yao, W. Brightened spin–triplet interlayer excitons and optical selection rules in van der Waals heterobilayers. 2D Mater. 5, 035021 (2018).

    Article  Google Scholar 

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

    ADS  Article  Google Scholar 

Download references


This work was supported primarily by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division under contract no. DE-AC02-05-CH11231 (van der Waals heterostructures program, KCWF16). PLE spectroscopy of the heterostructure is supported by the US Army Research Office under MURI award W911NF-17-1-0312. The growth of hBN crystals was supported by the Elemental Strategy Initiative conducted by the MEXT, Japan and JSPS KAKENHI grant no. JP15K21722. S.T. acknowledges support from an NSF DMR 1552220 NSF CAREER award for the growth of WS2 and WSe2 crystals. E.C.R. acknowledges support from the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program. C.-S.Y. acknowledges support from grant no. 107-2112-M-003-014-MY3 from the Ministry of Science and Technology.

Author information

Authors and Affiliations



F.W. and C.J. conceived the research. C.J., E.C.R. and C.-S.Y. built the optical set-up. C.J., E.C.R. and D.W. carried out optical measurements. C.J., F.W. and E.C.R. performed theoretical analysis. E.C.R., D.W., M.I.B.U. and Z.Z. fabricated van der Waals heterostructures. Y.Q., Y.S., S.T., J.C. and A.Z. grew the WSe2 and WS2 crystals. K.W. and T.T. grew the hBN crystals. All authors discussed the results and wrote the manuscript.

Corresponding author

Correspondence to Feng Wang.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information: Nature Physics thanks Paulina Plochocka, Jun Yan and Ziliang Ye for their contribution to the peer review of this work.

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

Supplementary information

Supplementary Information

Supplementary Figs. 1–4 and refs. 35–38.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Jin, C., Regan, E.C., Wang, D. et al. Identification of spin, valley and moiré quasi-angular momentum of interlayer excitons. Nat. Phys. 15, 1140–1144 (2019).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing