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Excitonic metal and non-Fermi liquid behavior in twisted double bilayer graphene near charge neutrality

Ghorai, U and Ghosh, A and Chakraborty, S and Das, A and Sensarma, R (2023) Excitonic metal and non-Fermi liquid behavior in twisted double bilayer graphene near charge neutrality. In: Physical Review B, 108 (4).

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Official URL: https://doi.org/10.1103/PhysRevB.108.045117


Twisted double bilayer graphene is a compensated semimetal near the charge neutrality point with the presence of small electron and hole pockets in its band structure. We show that strong Coulomb attraction between the electrons and holes can lead to the formation of indirect excitons. Condensation of these excitons at low temperature creates an excitonic metal with charge density wave order for an appropriate range of interaction strength. This has interesting implications for low-temperature transport in the system as a function of carrier density and temperature. The reorganization of the single-particle excitations and their density of states in the excitonic metal can lead to peaks in resistivity as a function of carrier density, recently seen in experiments at low temperatures. The fluctuations of the Landau damped order parameter in the quantum critical metal lead to non-Fermi liquid behavior, which can explain the sublinear Formula Presented dependence of the resistance near the charge neutrality point.

Item Type: Journal Article
Publication: Physical Review B
Publisher: American Physical Society
Additional Information: The copyright for this article belongs to the Authors.
Keywords: Carrier concentration; Charge density; Excitons; Fermi liquids; Fermions; Graphene; Temperature, Bilayer Graphene; Charge neutrality; Charge-density-waves; Coulomb attraction; Electrons and holes; Excitonics; Indirect excitons; Lows-temperatures; Neutrality point; Non-fermi-liquid behaviour, Charge density waves
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 27 Nov 2023 09:40
Last Modified: 27 Nov 2023 09:40
URI: https://eprints.iisc.ac.in/id/eprint/82907

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