Quantum critical behaviour in magic-angle twisted bilayer graphene
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2108.07753.pdf
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Author(s)
Jaoui, Alexandre
Das, Ipsita
Di Battista, Giorgio
Díez-Mérida, Jaime
Lu, Xiaobo
Watanabe, Kenji
Taniguchi, Takashi
Ishizuka, Hiroaki
Levitov, Leonid
Efetov, Dmitri K
Date Issued
April 11, 2022
Journal
Nature Physics
Publisher
Springer Science and Business Media LLC
Citation
Jaoui, Alexandre, Das, Ipsita, Di Battista, Giorgio, Díez-Mérida, Jaime, Lu, Xiaobo et al. 2022. "Quantum critical behaviour in magic-angle twisted bilayer graphene." Nature Physics.
Version
Original manuscript
Abstract
The flat bands of magic-angle twisted bilayer graphene (MATBG) host
strongly-correlated electronic phases such as correlated insulators,
superconductors and a strange-metal state. The latter state, believed to be key
for understanding the electronic properties of MATBG, is obscured by various
phase transitions and thus could not be unequivocally differentiated from a
metal undergoing frequent electron-phonon collisions. Here, we report transport
measurements in superconducting MATBG in which the correlated insulator states
are suppressed by screening. The uninterrupted metallic ground state shows
resistivity that is linear in temperature over three decades and spans a broad
range of doping including those where a correlation-driven Fermi surface
reconstruction occurs. This strange-metal behavior is distinguished by
Planckian scattering rates and a linear magnetoresistivity. In contrast, near
charge neutrality or a fully-filled flat band, as well as for devices twisted
away from the magic angle, we observe the archetypal Fermi liquid behavior. Our
measurements demonstrate the existence of a quantum critical phase whose
fluctuations dominate the metallic ground state throughout a continuum of
doping. Further, we observe a transition to the strange metal upon suppression
of the superconducting order, suggesting a relationship between quantum
fluctuations and superconductivity in MATBG.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1038/s41567-022-01556-5
