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Vanishing Thermal Equilibration for Hole-Conjugate Fractional Quantum Hall States in Graphene

Srivastav, SK and Kumar, R and Spånslätt, C and Watanabe, K and Taniguchi, T and Mirlin, AD and Gefen, Y and Das, A (2021) Vanishing Thermal Equilibration for Hole-Conjugate Fractional Quantum Hall States in Graphene. In: Physical Review Letters, 126 (21).

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Official URL: https://doi.org/10.1103/PhysRevLett.126.216803


Transport through edge channels is responsible for conduction in quantum Hall (QH) phases. Robust quantized values of charge and thermal conductances dictated by bulk topology appear when equilibration processes become dominant. We report on measurements of electrical and thermal conductances of integer and fractional QH phases, realized in hexagonal boron nitride encapsulated graphite-gated bilayer graphene devices for both electron and hole doped sides with different valley and orbital symmetries. Remarkably, for complex edges at filling factors ν=53 and 83, closely related to the paradigmatic hole-conjugate ν=23 phase, we find quantized thermal conductance whose values (3κ0T and 4κ0T, respectively where κ0T is the thermal conductance quantum) are markedly inconsistent with the values dictated by topology (1κ0T and 2κ0T, respectively). The measured thermal conductance values remain insensitive to different symmetries, suggesting its universal nature. Our findings are supported by a theoretical analysis, which indicates that, whereas electrical equilibration at the edge is established over a finite length scale, the thermal equilibration length diverges for strong electrostatic interaction. Our results elucidate the subtle nature of crossover from coherent, mesoscopic to topology-dominated transport. © 2021 American Physical Society.

Item Type: Journal Article
Publication: Physical Review Letters
Publisher: American Physical Society
Additional Information: The copyright for this article belongs to Authors
Keywords: Graphene devices; III-V semiconductors; Quantum chemistry; Quantum theory; Thermal conductivity; Topology, Bilayer Graphene; Equilibration process; Fractional quantum Hall state; Hexagonal boron nitride; Orbital symmetries; Quantized thermal conductance; Thermal conductance; Thermal equilibrations, Graphene
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 26 Aug 2021 09:54
Last Modified: 26 Aug 2021 09:54
URI: http://eprints.iisc.ac.in/id/eprint/69334

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