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Title: Correlated insulating and superconducting states in twisted bilayer graphene below the magic angle

Abstract

The emergence of flat bands and correlated behaviors in “magic angle” twisted bilayer graphene (tBLG) has sparked tremendous interest, though its many aspects are under intense debate. Here we report observation of both superconductivity and the Mott-like insulating state in a tBLG device with a twist angle of ~0.93°, which is smaller than the magic angle by 15%. At an electron concentration of ±5 electrons/moiré unit cell, we observe a narrow resistance peak with an activation energy gap ~0.1 meV. This indicates additional correlated insulating state, and is consistent with theory predicting a high-energy flat band. At doping of ±12 electrons/moiré unit cell we observe resistance peaks arising from the Dirac points in the spectrum. Our results reveal that the “magic” range of tBLG is in fact larger than what is previously expected, and provide a wealth of new information to help decipher the strongly correlated phenomena observed in tBLG.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1];  [1]; ORCiD logo [1];  [1];  [1]; ORCiD logo [3];  [3]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [1]
  1. The Ohio State Univ., Columbus, OH (United States)
  2. Univ. of Texas at Dallas, Richardson, TX (United States)
  3. National Inst. of Materials Science, Ibaraki (Japan)
Publication Date:
Research Org.:
Univ. of California, Riverside, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1611466
Grant/Contract Number:  
SC0010597
Resource Type:
Accepted Manuscript
Journal Name:
Science Advances
Additional Journal Information:
Journal Volume: 5; Journal Issue: 9; Journal ID: ISSN 2375-2548
Publisher:
AAAS
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Science & Technology - Other Topics

Citation Formats

Codecido, Emilio, Wang, Qiyue, Koester, Ryan, Che, Shi, Tian, Haidong, Lv, Rui, Tran, Son, Watanabe, Kenji, Taniguchi, Takashi, Zhang, Fan, Bockrath, Marc, and Lau, Chun Ning. Correlated insulating and superconducting states in twisted bilayer graphene below the magic angle. United States: N. p., 2019. Web. https://doi.org/10.1126/sciadv.aaw9770.
Codecido, Emilio, Wang, Qiyue, Koester, Ryan, Che, Shi, Tian, Haidong, Lv, Rui, Tran, Son, Watanabe, Kenji, Taniguchi, Takashi, Zhang, Fan, Bockrath, Marc, & Lau, Chun Ning. Correlated insulating and superconducting states in twisted bilayer graphene below the magic angle. United States. https://doi.org/10.1126/sciadv.aaw9770
Codecido, Emilio, Wang, Qiyue, Koester, Ryan, Che, Shi, Tian, Haidong, Lv, Rui, Tran, Son, Watanabe, Kenji, Taniguchi, Takashi, Zhang, Fan, Bockrath, Marc, and Lau, Chun Ning. Fri . "Correlated insulating and superconducting states in twisted bilayer graphene below the magic angle". United States. https://doi.org/10.1126/sciadv.aaw9770. https://www.osti.gov/servlets/purl/1611466.
@article{osti_1611466,
title = {Correlated insulating and superconducting states in twisted bilayer graphene below the magic angle},
author = {Codecido, Emilio and Wang, Qiyue and Koester, Ryan and Che, Shi and Tian, Haidong and Lv, Rui and Tran, Son and Watanabe, Kenji and Taniguchi, Takashi and Zhang, Fan and Bockrath, Marc and Lau, Chun Ning},
abstractNote = {The emergence of flat bands and correlated behaviors in “magic angle” twisted bilayer graphene (tBLG) has sparked tremendous interest, though its many aspects are under intense debate. Here we report observation of both superconductivity and the Mott-like insulating state in a tBLG device with a twist angle of ~0.93°, which is smaller than the magic angle by 15%. At an electron concentration of ±5 electrons/moiré unit cell, we observe a narrow resistance peak with an activation energy gap ~0.1 meV. This indicates additional correlated insulating state, and is consistent with theory predicting a high-energy flat band. At doping of ±12 electrons/moiré unit cell we observe resistance peaks arising from the Dirac points in the spectrum. Our results reveal that the “magic” range of tBLG is in fact larger than what is previously expected, and provide a wealth of new information to help decipher the strongly correlated phenomena observed in tBLG.},
doi = {10.1126/sciadv.aaw9770},
journal = {Science Advances},
number = 9,
volume = 5,
place = {United States},
year = {2019},
month = {9}
}

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Cited by: 16 works
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    Works referencing / citing this record:

    In situ growth of graphene on hexagonal boron nitride for electronic transport applications
    journal, January 2020

    • Arjmandi-Tash, Hadi
    • Journal of Materials Chemistry C, Vol. 8, Issue 2
    • DOI: 10.1039/c9tc04779d