Abstract
Van der Waals heterostructures obtained via stacking and twisting have been used to create moiré superlattices1, enabling new optical and electronic properties in solid-state systems. Moiré lattices in twisted bilayers of transition metal dichalcogenides (TMDs) result in exciton trapping2,3,4,5, host Mott insulating and superconducting states6 and act as unique Hubbard systems7,8,9 whose correlated electronic states can be detected and manipulated optically. Structurally, these twisted heterostructures feature atomic reconstruction and domain formation10,11,12,13,14. However, due to the nanoscale size of moiré domains, the effects of atomic reconstruction on the electronic and excitonic properties have not been systematically investigated. Here we use near-0°-twist-angle MoSe2/MoSe2 bilayers with large rhombohedral AB/BA domains15 to directly probe the excitonic properties of individual domains with far-field optics. We show that this system features broken mirror/inversion symmetry, with the AB and BA domains supporting interlayer excitons with out-of-plane electric dipole moments in opposite directions. The dipole orientation of ground-state Γ–K interlayer excitons can be flipped with electric fields, while higher-energy K–K interlayer excitons undergo field-asymmetric hybridization with intralayer K–K excitons. Our study reveals the impact of crystal symmetry on TMD excitons and points to new avenues for realizing topologically non-trivial systems16,17, exotic metasurfaces18, collective excitonic phases19 and quantum emitter arrays20,21 via domain-pattern engineering.
This is a preview of subscription content, access via your institution
Access options
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 / 30 days
cancel any time
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
Data availability
The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
References
Cao, Y. et al. Unconventional superconductivity in magic-angle graphene superlattices. Nature 556, 43–50 (2018).
Seyler, K. L. et al. Signatures of moiré-trapped valley excitons in MoSe2/WSe2 heterobilayers. Nature 567, 66–70 (2019).
Tran, K. et al. Evidence for moiré excitons in van der Waals heterostructures. Nature 567, 71–75 (2019).
Jin, C. et al. Observation of moiré excitons in WSe2/WS2 heterostructure superlattices. Nature 567, 76–80 (2019).
Alexeev, E. M. et al. Resonantly hybridized excitons in moiré superlattices in van der Waals heterostructures. Nature 567, 81–86 (2019).
Wang, L. et al. Correlated electronic phases in twisted bilayer transition metal dichalcogenides. Nat. Mater. https://doi.org/10.1038/s41563-020-0708-6 (2020).
Tang, Y. et al. Simulation of Hubbard model physics in WSe2/WS2 moiré superlattices. Nature 579, 353–358 (2020).
Regan, E. C. et al. Mott and generalized Wigner crystal states in WSe2/WS2 moiré superlattices. Nature 579, 359–363 (2020).
Shimazaki, Y. et al. Strongly correlated electrons and hybrid excitons in a moiré heterostructure. Nature 580, 472–477 (2020).
Enaldiev, V. V., Zólyomi, V., Yelgel, C., Magorrian, S. J. & Fal’ko, V. I. Stacking domains and dislocation networks in marginally twisted bilayers of transition metal dichalcogenides. Phys. Rev. Lett. 124, 206101 (2020).
Weston, A. et al. Atomic reconstruction in twisted bilayers of transition metal dichalcogenides. Nat. Nanotechnol. https://doi.org/10.1038/s41565-020-0682-9 (2020).
McGilly, L. J. et al. Visualization of moiré superlattices. Nat. Nanotechnol. https://doi.org/10.1038/s41565-020-0708-3 (2020).
Sushko, A. et al. High resolution imaging of reconstructed domains and moire patterns in functional van der Waals heterostructure devices. Preprint at http://arxiv.org/abs/1912.07446 (2019).
Rosenberger, M. R. et al. Twist angle-dependent atomic reconstruction and moiré patterns in transition metal dichalcogenide heterostructures. ACS Nano 14, 4550–4558 (2020).
Toh, R. J., Sofer, Z., Luxa, J., Sedmidubský, D. & Pumera, M. 3R phase of MoS2 and WS2 outperforms the corresponding 2H phase for hydrogen evolution. Chem. Commun. 53, 3054–3057 (2017).
Wu, F., Lovorn, T. & MacDonald, A. H. Topological exciton bands in moiré heterojunctions. Phys. Rev. Lett. 118, 147401 (2017).
Perczel, J. et al. Topological quantum optics in two-dimensional atomic arrays. Phys. Rev. Lett. 119, 023603 (2017).
Bekenstein, R. et al. Quantum metasurfaces with atom arrays. Nat. Phys. 16, 676–681 (2020).
Byrnes, T., Recher, P. & Yamamoto, Y. Mott transitions of exciton polaritons and indirect excitons in a periodic potential. Phys. Rev. B 81, 205312 (2010).
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).
Wu, F., Lovorn, T. & MacDonald, A. H. Theory of optical absorption by interlayer excitons in transition metal dichalcogenide heterobilayers. Phys. Rev. B 97, 035306 (2018).
Yoo, H. et al. Atomic and electronic reconstruction at the van der Waals interface in twisted bilayer graphene. Nat. Mater. 18, 448–453 (2019).
Woods, C. R. et al. Macroscopic self-reorientation of interacting two-dimensional crystals. Nat. Commun. 7, 10800 (2016).
Wang, Z., Chiu, Y.-H., Honz, K., Mak, K. F. & Shan, J. Electrical tuning of interlayer exciton gases in WSe2 bilayers. Nano Lett. 18, 137–143 (2018).
Jauregui, L. A. et al. Electrical control of interlayer exciton dynamics in atomically thin heterostructures. Science 366, 870–875 (2019).
Scuri, G. et al. Large excitonic reflectivity of monolayer MoSe2 encapsulated in hexagonal boron nitride. Phys. Rev. Lett. 120, 037402 (2018).
Zhou, Y. et al. Controlling excitons in an atomically thin membrane with a mirror. Phys. Rev. Lett. 124, 027401 (2020).
Horng, J. et al. Observation of interlayer excitons in MoSe2 single crystals. Phys. Rev. B 97, 241404 (2018).
Gerber, I. C. et al. Interlayer excitons in bilayer MoS2 with strong oscillator strength up to room temperature. Phys. Rev. B 99, 035443 (2019).
Liu, K. et al. Evolution of interlayer coupling in twisted molybdenum disulfide bilayers. Nat. Commun. 5, 4966 (2014).
Kunstmann, J. et al. Momentum-space indirect interlayer excitons in transition-metal dichalcogenide van der Waals heterostructures. Nat. Phys. 14, 801–805 (2018).
Deilmann, T. & Thygesen, K. S. Interlayer excitons with large optical amplitudes in layered van der Waals materials. Nano Lett. 18, 2984–2989 (2018).
Miller, B. et al. Long-lived direct and indirect interlayer excitons in van der Waals heterostructures. Nano Lett. 17, 5229–5237 (2017).
Daniels, J. M., Machnikowski, P. & Kuhn, T. Excitons in quantum dot molecules: Coulomb coupling, spin-orbit effects, and phonon-induced line broadening. Phys. Rev. B 88, 205307 (2013).
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).
Hubert, C. et al. Attractive dipolar coupling between stacked exciton fluids. Phys. Rev. X 9, 021026 (2019).
Ribeiro-Palau, R. et al. Twistable electronics with dynamically rotatable heterostructures. Science 361, 690–693 (2018).
Sammon, M. & Shklovskii, B. I. Attraction of indirect excitons in van der Waals heterostructures with three semiconducting layers. Phys. Rev. B 99, 165403 (2019).
Stern, M., Umansky, V. & Bar-Joseph, I. Exciton liquid in coupled quantum wells. Science 343, 55–57 (2014).
Wang, Z. et al. Evidence of high-temperature exciton condensation in two-dimensional atomic double layers. Nature 574, 76–80 (2019).
Brown, L. et al. Twinning and twisting of tri- and bilayer graphene. Nano Lett. 12, 1609–1615 (2012).
Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169 (1996).
Bronsema, K. D., De Boer, J. L. & Jellinek, F. On the structure of molybdenum diselenide and disulfide. Z. Anorg. Allg. Chem. 540, 15–17 (1986).
Acknowledgements
We thank B. Urbaszek for helpful discussions. We acknowledge support from the DoD Vannevar Bush Faculty Fellowship (N00014-16-1-2825 for H.P., N00014-18-1-2877 for P.K.), NSF (PHY-1506284 for H.P. and M.D.L.), NSF CUA (PHY-1125846 for H.P. and M.D.L.), AFOSR MURI (FA9550-17-1-0002), ARL (W911NF1520067 for H.P. and M.D.L.), the Gordon and Betty Moore Foundation (GBMF4543 for P.K.), ONR MURI (N00014-15-1-2761 for P.K.), and Samsung Electronics (for P.K. and H.P.). V.I.F. acknowledges EPSRC grants no. EP/S019367/1, EP/S030719/1, EP/N010345/1, ERC Synergy Grant Hetero2D, Lloyd’s Register Foundation Nanotechnology Grant, European Graphene Flagship Project and European Quantum Technologies Project 2D-SIPC. The device fabrication was carried out at the Harvard Center for Nanoscale Systems. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan and the CREST (JPMJCR15F3), JST. D.B. acknowledges support from the Summer Undergraduate Research Fellowship at Caltech.
Author information
Authors and Affiliations
Contributions
H.P., P.K., J.S., Y.Z., G.S., H.Y. and D.S.W. conceived the study, and J.S., Y.Z., G.S., T.I.A, A.Y.J., R.J.G., D.B. and A.M.M.V. fabricated the devices and performed the optical spectroscopy. H.P. V.I.F. J.S., Y.Z., G.S., V.Z., T.I.A. and D.S.W. analysed the data. V.I.F., V.Z. and S.J.M. performed the DFT calculations. H.Y. performed electron microscopy measurements. H.H. performed MoSe2 crystal growth. T.T. and K.W. performed h-BN crystal growth. J.S., Y.Z., G.S., T.I.A, M.D.L., P.K., V.I.F. and H.P. wrote the manuscript with extensive input from all authors. H.P., V.I.F., P.K. and M.D.L. supervised the project.
Corresponding authors
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 Figs. 1–7.
Rights and permissions
About this article
Cite this article
Sung, J., Zhou, Y., Scuri, G. et al. Broken mirror symmetry in excitonic response of reconstructed domains in twisted MoSe2/MoSe2 bilayers. Nat. Nanotechnol. 15, 750–754 (2020). https://doi.org/10.1038/s41565-020-0728-z
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41565-020-0728-z
This article is cited by
-
Non-volatile electrical polarization switching via domain wall release in 3R-MoS2 bilayer
Nature Communications (2024)
-
Twistronics and moiré excitonic physics in van der Waals heterostructures
Frontiers of Physics (2024)
-
Excitonic devices based on two-dimensional transition metal dichalcogenides van der Waals heterostructures
Frontiers of Chemical Science and Engineering (2024)
-
Sequential order dependent dark-exciton modulation in bi-layered TMD heterostructure
Nature Communications (2023)
-
Excitons in mesoscopically reconstructed moiré heterostructures
Nature Nanotechnology (2023)