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Title: Magic in twisted transition metal dichalcogenide bilayers

Abstract

The long-wavelength moiré superlattices in twisted 2D structures have emerged as a highly tunable platform for strongly correlated electron physics. We study the moiré bands in twisted transition metal dichalcogenide homobilayers, focusing on WSe2, at small twist angles using a combination of first principles density functional theory, continuum modeling, and Hartree-Fock approximation. We reveal the rich physics at small twist angles θ < 4°, and identify a particular magic angle at which the top valence moiré band achieves almost perfect flatness. In the vicinity of this magic angle, we predict the realization of a generalized Kane-Mele model with a topological flat band, interaction-driven Haldane insulator, and Mott insulators at the filling of one hole per moiré unit cell. The combination of flat dispersion and uniformity of Berry curvature near the magic angle holds promise for realizing fractional quantum anomalous Hall effect at fractional filling. We also identify twist angles favorable for quantum spin Hall insulators and interaction-induced quantum anomalous Hall insulators at other integer fillings.

Authors:
ORCiD logo [1];  [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Publication Date:
Research Org.:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org.:
USDOE Office of Science (SC); Simons Foundation; David and Lucile Packard Foundation
OSTI Identifier:
1904375
Grant/Contract Number:  
SC0018945; SC0020149
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 12; Journal Issue: 1; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; electronic properties and materials; quantum Hall; topological insulators; two-dimensional materials

Citation Formats

Devakul, Trithep, Crépel, Valentin, Zhang, Yang, and Fu, Liang. Magic in twisted transition metal dichalcogenide bilayers. United States: N. p., 2021. Web. doi:10.1038/s41467-021-27042-9.
Devakul, Trithep, Crépel, Valentin, Zhang, Yang, & Fu, Liang. Magic in twisted transition metal dichalcogenide bilayers. United States. https://doi.org/10.1038/s41467-021-27042-9
Devakul, Trithep, Crépel, Valentin, Zhang, Yang, and Fu, Liang. 2021. "Magic in twisted transition metal dichalcogenide bilayers". United States. https://doi.org/10.1038/s41467-021-27042-9. https://www.osti.gov/servlets/purl/1904375.
@article{osti_1904375,
title = {Magic in twisted transition metal dichalcogenide bilayers},
author = {Devakul, Trithep and Crépel, Valentin and Zhang, Yang and Fu, Liang},
abstractNote = {The long-wavelength moiré superlattices in twisted 2D structures have emerged as a highly tunable platform for strongly correlated electron physics. We study the moiré bands in twisted transition metal dichalcogenide homobilayers, focusing on WSe2, at small twist angles using a combination of first principles density functional theory, continuum modeling, and Hartree-Fock approximation. We reveal the rich physics at small twist angles θ < 4°, and identify a particular magic angle at which the top valence moiré band achieves almost perfect flatness. In the vicinity of this magic angle, we predict the realization of a generalized Kane-Mele model with a topological flat band, interaction-driven Haldane insulator, and Mott insulators at the filling of one hole per moiré unit cell. The combination of flat dispersion and uniformity of Berry curvature near the magic angle holds promise for realizing fractional quantum anomalous Hall effect at fractional filling. We also identify twist angles favorable for quantum spin Hall insulators and interaction-induced quantum anomalous Hall insulators at other integer fillings.},
doi = {10.1038/s41467-021-27042-9},
url = {https://www.osti.gov/biblio/1904375}, journal = {Nature Communications},
issn = {2041-1723},
number = 1,
volume = 12,
place = {United States},
year = {Thu Nov 18 00:00:00 EST 2021},
month = {Thu Nov 18 00:00:00 EST 2021}
}

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