Observation of moiré excitons in WSe₂/WS₂ heterostructure superlattices

Chenhao Jin^#¹, Emma C Regan^#^{1

2}, Aiming Yan^{1

3}, M Iqbal Bakti Utama^{1

4}, Danqing Wang^{1

2}, Sihan Zhao¹, Ying Qin⁵, Sijie Yang⁵, Zhiren Zheng¹, Shenyang Shi^{1

6}, Kenji Watanabe⁷, Takashi Taniguchi⁷, Sefaattin Tongay⁵, Alex Zettl^{1

3

8}, Feng Wang^{9

10

11}

Affiliations

¹ Department of Physics, University of California at Berkeley, Berkeley, CA, USA.
² Graduate Group in Applied Science and Technology, University of California at Berkeley, Berkeley, CA, USA.
³ Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁴ Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, CA, USA.
⁵ School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA.
⁶ Department of Physics, Fudan University, Shanghai, China.
⁷ National Institute for Materials Science, Tsukuba, Japan.
⁸ Kavli Energy NanoSciences Institute at University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁹ Department of Physics, University of California at Berkeley, Berkeley, CA, USA. fengwang76@berkeley.edu.
¹⁰ Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. fengwang76@berkeley.edu.
¹¹ Kavli Energy NanoSciences Institute at University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, USA. fengwang76@berkeley.edu.

^# Contributed equally.

PMID: 30804525
DOI: 10.1038/s41586-019-0976-y

Free article

Observation of moiré excitons in WSe₂/WS₂ heterostructure superlattices

Chenhao Jin et al. Nature. 2019 Mar.

Free article

. 2019 Mar;567(7746):76-80.

doi: 10.1038/s41586-019-0976-y. Epub 2019 Feb 25.

Authors

Affiliations

¹ Department of Physics, University of California at Berkeley, Berkeley, CA, USA.
² Graduate Group in Applied Science and Technology, University of California at Berkeley, Berkeley, CA, USA.
³ Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁴ Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, CA, USA.
⁵ School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA.
⁶ Department of Physics, Fudan University, Shanghai, China.
⁷ National Institute for Materials Science, Tsukuba, Japan.
⁸ Kavli Energy NanoSciences Institute at University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁹ Department of Physics, University of California at Berkeley, Berkeley, CA, USA. fengwang76@berkeley.edu.
¹⁰ Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. fengwang76@berkeley.edu.
¹¹ Kavli Energy NanoSciences Institute at University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, USA. fengwang76@berkeley.edu.

^# Contributed equally.

PMID: 30804525
DOI: 10.1038/s41586-019-0976-y

Erratum in

Author Correction: Observation of moiré excitons in WSe₂/WS₂ heterostructure superlattices.
Jin C, Regan EC, Yan A, Utama MIB, Wang D, Zhao S, Qin Y, Yang S, Zheng Z, Shi S, Watanabe K, Taniguchi T, Tongay S, Zettl A, Wang F. Jin C, et al. Nature. 2019 May;569(7757):E7. doi: 10.1038/s41586-019-1206-3. Nature. 2019. PMID: 31065056

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 (WSe₂/WS₂) heterostructures in which the layers are closely aligned. These moiré exciton states manifest as multiple emergent peaks around the original WSe₂ A exciton resonance in the absorption spectra, and they exhibit gate dependences that are distinct from that of the A exciton in WSe₂ monolayers and in WSe₂/WS₂ 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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Comment in

Materials in flatland twist and shine.
Urbaszek B, Srivastava A. Urbaszek B, et al. Nature. 2019 Mar;567(7746):39-40. doi: 10.1038/d41586-019-00704-x. Nature. 2019. PMID: 30842634 No abstract available.

References

1. Hunt, B. et al. Massive Dirac fermions and Hofstadter butterfly in a van der Waals heterostructure. Science 340, 1427–1430 (2013). - DOI
1. Ponomarenko, L. A. et al. Cloning of Dirac fermions in graphene superlattices. Nature 497, 594–597 (2013). - DOI
1. Dean, C. R. et al. Hofstadter’s butterfly and the fractal quantum Hall effect in moiré superlattices. Nature 497, 598–602 (2013). - DOI
1. Cao, Y. et al. Unconventional superconductivity in magic-angle graphene superlattices. Nature 556, 43–50 (2018). - DOI
1. Cao, Y. et al. Correlated insulator behaviour at half-filling in magic-angle graphene superlattices. Nature 556, 80–84 (2018). - DOI

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Observation of moiré excitons in WSe₂/WS₂ heterostructure superlattices

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Observation of moiré excitons in WSe₂/WS₂ heterostructure superlattices

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