Observation of moiré excitons in WSe 2 /WS 2 heterostructure superlattices

Chenhao Jin, Emma C. Regan, Aiming Yan, M. Iqbal Bakti Utama, Danqing Wang, Sihan Zhao, Ying Qin, Sijie Yang, Zhiren Zheng, Shenyang Shi, Kenji Watanabe, Takashi Taniguchi, Sefaattin Tongay, Alex Zettl, Feng Wang

Research output: Contribution to journalLetter

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Abstract

Moiré superlattices enable the generation of new quantum phenomena in two-dimensional heterostructures, in which the interactions between the atomically thin layers qualitatively change the electronic band structure of the superlattice. For example, mini-Dirac points, tunable Mott insulator states and the Hofstadter butterfly pattern can emerge in different types of graphene/boron nitride moiré superlattices, whereas correlated insulating states and superconductivity have been reported in twisted bilayer graphene moiré superlattices 1–12 . In addition to their pronounced effects on single-particle states, moiré superlattices have recently been predicted to host excited states such as moiré exciton bands 13–15 . Here we report the observation of moiré superlattice exciton states in tungsten diselenide/tungsten disulfide (WSe 2 /WS 2 ) heterostructures in which the layers are closely aligned. These moiré exciton states manifest as multiple emergent peaks around the original WSe 2 A exciton resonance in the absorption spectra, and they exhibit gate dependences that are distinct from that of the A exciton in WSe 2 monolayers and in WSe 2 /WS 2 heterostructures with large twist angles. These phenomena can be described by a theoretical model in which the periodic moiré potential is much stronger than the exciton kinetic energy and generates multiple flat exciton minibands. The moiré exciton bands provide an attractive platform from which to explore and control excited states of matter, such as topological excitons and a correlated exciton Hubbard model, in transition-metal dichalcogenides.

Original languageEnglish (US)
Pages (from-to)76-80
Number of pages5
JournalNature
Volume567
Issue number7746
DOIs
StatePublished - Mar 7 2019

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Cite this

Jin, C., Regan, E. C., Yan, A., Iqbal Bakti Utama, M., Wang, D., Zhao, S., ... Wang, F. (2019). Observation of moiré excitons in WSe 2 /WS 2 heterostructure superlattices Nature, 567(7746), 76-80. https://doi.org/10.1038/s41586-019-0976-y

Observation of moiré excitons in WSe 2 /WS 2 heterostructure superlattices . / Jin, Chenhao; Regan, Emma C.; Yan, Aiming; Iqbal Bakti Utama, M.; Wang, Danqing; Zhao, Sihan; Qin, Ying; Yang, Sijie; Zheng, Zhiren; Shi, Shenyang; Watanabe, Kenji; Taniguchi, Takashi; Tongay, Sefaattin; Zettl, Alex; Wang, Feng.

In: Nature, Vol. 567, No. 7746, 07.03.2019, p. 76-80.

Research output: Contribution to journalLetter

Jin, C, Regan, EC, Yan, A, Iqbal Bakti Utama, M, Wang, D, Zhao, S, Qin, Y, Yang, S, Zheng, Z, Shi, S, Watanabe, K, Taniguchi, T, Tongay, S, Zettl, A & Wang, F 2019, ' Observation of moiré excitons in WSe 2 /WS 2 heterostructure superlattices ', Nature, vol. 567, no. 7746, pp. 76-80. https://doi.org/10.1038/s41586-019-0976-y
Jin C, Regan EC, Yan A, Iqbal Bakti Utama M, Wang D, Zhao S et al. Observation of moiré excitons in WSe 2 /WS 2 heterostructure superlattices Nature. 2019 Mar 7;567(7746):76-80. https://doi.org/10.1038/s41586-019-0976-y
Jin, Chenhao ; Regan, Emma C. ; Yan, Aiming ; Iqbal Bakti Utama, M. ; Wang, Danqing ; Zhao, Sihan ; Qin, Ying ; Yang, Sijie ; Zheng, Zhiren ; Shi, Shenyang ; Watanabe, Kenji ; Taniguchi, Takashi ; Tongay, Sefaattin ; Zettl, Alex ; Wang, Feng. / Observation of moiré excitons in WSe 2 /WS 2 heterostructure superlattices In: Nature. 2019 ; Vol. 567, No. 7746. pp. 76-80.
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title = "Observation of moir{\'e} excitons in WSe 2 /WS 2 heterostructure superlattices",
abstract = "Moir{\'e} superlattices enable the generation of new quantum phenomena in two-dimensional heterostructures, in which the interactions between the atomically thin layers qualitatively change the electronic band structure of the superlattice. For example, mini-Dirac points, tunable Mott insulator states and the Hofstadter butterfly pattern can emerge in different types of graphene/boron nitride moir{\'e} superlattices, whereas correlated insulating states and superconductivity have been reported in twisted bilayer graphene moir{\'e} superlattices 1–12 . In addition to their pronounced effects on single-particle states, moir{\'e} superlattices have recently been predicted to host excited states such as moir{\'e} exciton bands 13–15 . Here we report the observation of moir{\'e} superlattice exciton states in tungsten diselenide/tungsten disulfide (WSe 2 /WS 2 ) heterostructures in which the layers are closely aligned. These moir{\'e} exciton states manifest as multiple emergent peaks around the original WSe 2 A exciton resonance in the absorption spectra, and they exhibit gate dependences that are distinct from that of the A exciton in WSe 2 monolayers and in WSe 2 /WS 2 heterostructures with large twist angles. These phenomena can be described by a theoretical model in which the periodic moir{\'e} potential is much stronger than the exciton kinetic energy and generates multiple flat exciton minibands. The moir{\'e} exciton bands provide an attractive platform from which to explore and control excited states of matter, such as topological excitons and a correlated exciton Hubbard model, in transition-metal dichalcogenides.",
author = "Chenhao Jin and Regan, {Emma C.} and Aiming Yan and {Iqbal Bakti Utama}, M. and Danqing Wang and Sihan Zhao and Ying Qin and Sijie Yang and Zhiren Zheng and Shenyang Shi and Kenji Watanabe and Takashi Taniguchi and Sefaattin Tongay and Alex Zettl and Feng Wang",
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T1 - Observation of moiré excitons in WSe 2 /WS 2 heterostructure superlattices

AU - Jin, Chenhao

AU - Regan, Emma C.

AU - Yan, Aiming

AU - Iqbal Bakti Utama, M.

AU - Wang, Danqing

AU - Zhao, Sihan

AU - Qin, Ying

AU - Yang, Sijie

AU - Zheng, Zhiren

AU - Shi, Shenyang

AU - Watanabe, Kenji

AU - Taniguchi, Takashi

AU - Tongay, Sefaattin

AU - Zettl, Alex

AU - Wang, Feng

PY - 2019/3/7

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N2 - Moiré superlattices enable the generation of new quantum phenomena in two-dimensional heterostructures, in which the interactions between the atomically thin layers qualitatively change the electronic band structure of the superlattice. For example, mini-Dirac points, tunable Mott insulator states and the Hofstadter butterfly pattern can emerge in different types of graphene/boron nitride moiré superlattices, whereas correlated insulating states and superconductivity have been reported in twisted bilayer graphene moiré superlattices 1–12 . In addition to their pronounced effects on single-particle states, moiré superlattices have recently been predicted to host excited states such as moiré exciton bands 13–15 . Here we report the observation of moiré superlattice exciton states in tungsten diselenide/tungsten disulfide (WSe 2 /WS 2 ) heterostructures in which the layers are closely aligned. These moiré exciton states manifest as multiple emergent peaks around the original WSe 2 A exciton resonance in the absorption spectra, and they exhibit gate dependences that are distinct from that of the A exciton in WSe 2 monolayers and in WSe 2 /WS 2 heterostructures with large twist angles. These phenomena can be described by a theoretical model in which the periodic moiré potential is much stronger than the exciton kinetic energy and generates multiple flat exciton minibands. The moiré exciton bands provide an attractive platform from which to explore and control excited states of matter, such as topological excitons and a correlated exciton Hubbard model, in transition-metal dichalcogenides.

AB - Moiré superlattices enable the generation of new quantum phenomena in two-dimensional heterostructures, in which the interactions between the atomically thin layers qualitatively change the electronic band structure of the superlattice. For example, mini-Dirac points, tunable Mott insulator states and the Hofstadter butterfly pattern can emerge in different types of graphene/boron nitride moiré superlattices, whereas correlated insulating states and superconductivity have been reported in twisted bilayer graphene moiré superlattices 1–12 . In addition to their pronounced effects on single-particle states, moiré superlattices have recently been predicted to host excited states such as moiré exciton bands 13–15 . Here we report the observation of moiré superlattice exciton states in tungsten diselenide/tungsten disulfide (WSe 2 /WS 2 ) heterostructures in which the layers are closely aligned. These moiré exciton states manifest as multiple emergent peaks around the original WSe 2 A exciton resonance in the absorption spectra, and they exhibit gate dependences that are distinct from that of the A exciton in WSe 2 monolayers and in WSe 2 /WS 2 heterostructures with large twist angles. These phenomena can be described by a theoretical model in which the periodic moiré potential is much stronger than the exciton kinetic energy and generates multiple flat exciton minibands. The moiré exciton bands provide an attractive platform from which to explore and control excited states of matter, such as topological excitons and a correlated exciton Hubbard model, in transition-metal dichalcogenides.

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