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

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. 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. 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 providemore » 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.« less

Authors:
 [1];  [2];  [3];  [4];  [2];  [1];  [5];  [5];  [1];  [6];  [7];  [7];  [5];  [8];  [8]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Physics
  2. Univ. of California, Berkeley, CA (United States). Dept. of Physics; Univ. of California, Berkeley, CA (United States). Graduate Group in Applied Science and Technology
  3. Univ. of California, Berkeley, CA (United States). Dept. of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division
  4. Univ. of California, Berkeley, CA (United States). Dept. of Physics; Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Engineering
  5. Arizona State Univ., Tempe, AZ (United States). School for Engineering of Matter, Transport and Energy
  6. Univ. of California, Berkeley, CA (United States). Dept. of Physics; Fudan Univ., Shanghai (China). Dept. of Physics
  7. National Inst. for Materials Science, Tsukuba (Japan)
  8. Univ. of California, Berkeley, CA (United States). Dept. of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Kavli Energy NanoSciences Inst. at Univ. of California Berkeley and Lawrence Berkeley National Lab., Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division; USDOD
OSTI Identifier:
1571978
Grant/Contract Number:  
AC02-05CH11231; JP15K21722
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nature (London)
Additional Journal Information:
Journal Volume: 567; Journal Issue: 7746; Journal ID: ISSN 0028-0836
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

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, and Wang, Feng. Observation of moiré excitons in WSe2/WS2 heterostructure superlattices. United States: N. p., 2019. Web. doi: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 WSe2/WS2 heterostructure superlattices. United States. doi: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, and Wang, Feng. Mon . "Observation of moiré excitons in WSe2/WS2 heterostructure superlattices". United States. doi:10.1038/s41586-019-0976-y. https://www.osti.gov/servlets/purl/1571978.
@article{osti_1571978,
title = {Observation of moiré excitons in WSe2/WS2 heterostructure superlattices},
author = {Jin, Chenhao and Regan, Emma C. and Yan, Aiming and Iqbal Bakti Utama, M. and Wang, Danqing and Zhao, Sihan and Qin, Ying and Yang, Sijie and Zheng, Zhiren and Shi, Shenyang and Watanabe, Kenji and Taniguchi, Takashi and Tongay, Sefaattin and Zettl, Alex and Wang, Feng},
abstractNote = {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. 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. 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.},
doi = {10.1038/s41586-019-0976-y},
journal = {Nature (London)},
issn = {0028-0836},
number = 7746,
volume = 567,
place = {United States},
year = {2019},
month = {2}
}

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    Works referencing / citing this record:

    General synthesis of two-dimensional van der Waals heterostructure arrays
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    Nonlinear optics of two‐dimensional transition metal dichalcogenides
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