Vanishing Thermal Equilibration for Hole-Conjugate Fractional Quantum Hall States in Graphene
Artikel i vetenskaplig tidskrift, 2021

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.


Saurabh Kumar Srivastav

Indian Institute of Science

Ravi Kumar

Indian Institute of Science

Christian Spånslätt Rugarn

Karlsruher Institut für Technologie (KIT)

Chalmers, Mikroteknologi och nanovetenskap (MC2), Tillämpad kvantfysik

Kenji Watanabe

National Institute for Materials Science (NIMS)

Takashi Taniguchi

National Institute for Materials Science (NIMS)

Alexander D. Mirlin

Petersburg Nuclear Physics Institute (PNPI)

Karlsruher Institut für Technologie (KIT)

Landau Institute for Theoretical Physics

Yuval Gefen

Karlsruher Institut für Technologie (KIT)

Weizmann Institute of Science

Anindya Das

Indian Institute of Science

Physical Review Letters

0031-9007 (ISSN) 1079-7114 (eISSN)

Vol. 126 21 216803


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