Title: Evidence for moiré excitons in van der Waals heterostructures

Abstract

Recent advances in the isolation and stacking of monolayers of van der Waals materials have provided approaches for the preparation of quantum materials in the ultimate two-dimensional limit(1,2). In van der Waals heterostructures formed by stacking two monolayer semiconductors, lattice mismatch or rotational misalignment introduces an in-plane moire superlattice(3). It is widely recognized that the moire superlattice can modulate the electronic band structure of the material and lead to transport properties such as unconventional superconductivity(4) and insulating behaviour driven by correlations(5-7); however, the influence of the moire superlattice on optical properties has not been investigated experimentally. Here we report the observation of multiple interlayer exciton resonances with either positive or negative circularly polarized emission in a molybdenum diselenide/tungsten diselenide (MoSe₂/WSe₂) heterobilayer with a small twist angle. We attribute these resonances to excitonic ground and excited states confined within the moire potential. This interpretation is supported by recombination dynamics and by the dependence of these interlayer exciton resonances on twist angle and temperature. These results suggest the feasibility of engineering artificial excitonic crystals using van der Waals heterostructures for nanophotonics and quantum information applications.

Authors:

Tran, Kha ^[1]; Moody, Galan ^[2]; Wu, Fengcheng ^[3]; Lu, Xiaobo ^[4]; Choi, Junho ^[1]; Kim, Kyounghwan ^[5]; Rai, Amritesh ^[5]; Sanchez, Daniel A. ^[6]; Quan, Jiamin ^[1]; Singh, Akshay ^[1]; Embley, Jacob ^[1]; Zepeda, André ^[1]; Campbell, Marshall ^[1]; Autry, Travis ^[2]; Taniguchi, Takashi ^[7]; Watanabe, Kenji ^[7]; Lu, Nanshu ^[8]; Banerjee, Sanjay K. ^[5]; Silverman, Kevin L. ^[2]; Kim, Suenne ^[9] more »; Tutuc, Emanuel ^[5]; Yang, Li ^[4]; MacDonald, Allan H. ^[1]; Li, Xiaoqin ^[1] « less

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+ Show Author Affiliations

1. Univ. of Texas, Austin, TX (United States). Dept. of Physics and Center for Complex Quantum Systems
2. National Inst. of Standards and Technology (NIST), Boulder, CO (United States)
3. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division
4. Washington Univ., St. Louis, MO (United States). Dept. of Physics
5. Univ. of Texas, Austin, TX (United States). Microelectronics Research Center, Dept. of Electrical and Computer Engineering
6. Univ. of Texas, Austin, TX (United States). Dept. of Aerospace Engineering and Engineering Mechanics
7. National Inst. of Material Science, Ibaraki (Japan)
8. Univ. of Texas, Austin, TX (United States). Dept. of Aerospace Engineering and Engineering Mechanics, and Texas Materials Inst.
9. Hanyang Univ., Ansan (Korea). Dept. of Photonics and Nanoelectronics and Dept. of Applied Physics

Publication Date:

Mon Feb 25 00:00:00 EST 2019

Research Org.:

Argonne National Laboratory (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; National Science Foundation (NSF); Welch Foundation; China Scholarship Council; US Army Research Office (ARO); Air Force Research Laboratory (AFRL) - Air Force Office of Scientific Research (AFOSR); National Research Foundation of Korea (NRF); Japan Society for the Promotion of Science (JSPS) - KAKENHI

OSTI Identifier:

1503250

Grant/Contract Number:  

AC02-06CH11357

Resource Type:

Accepted Manuscript

Journal Name:

Nature (London)

Additional Journal Information:

Journal Name: Nature (London); Journal Volume: 567; Journal Issue: 7746; Journal ID: ISSN 0028-0836

Publisher:

Nature Publishing Group

Country of Publication:

United States

Language:

English

Subject:

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 42 ENGINEERING; 77 NANOSCIENCE AND NANOTECHNOLOGY