Determination of topological edge quantum numbers of fractional quantum Hall phases by thermal conductance measurements

To determine the topological quantum numbers of fractional quantum Hall (FQH) states hosting counter-propagating (CP) downstream (Nd) and upstream (Nu) edge modes, it is pivotal to study quantized transport both in the presence and absence of edge mode equilibration. While reaching the non-equilibrated regime is challenging for charge transport, we target here the thermal Hall conductance GQ, which is purely governed by edge quantum numbers Nd and Nu. Our experimental setup is realized with a hexagonal boron nitride (hBN) encapsulated graphite gated single layer graphene device. For temperatures up to 35 mK, our measured GQ at ν = 2/3 and 3/5 (with CP modes) match the quantized values of non-equilibrated regime (Nd + Nu)κ0T, where κ0T is a quanta of GQ. With increasing temperature, GQ decreases and eventually takes the value of the equilibrated regime ∣Nd - Nu∣κ0T. By contrast, at ν = 1/3 and 2/5 (without CP modes), GQ remains robustly quantized at Ndκ0T independent of the temperature. Thus, measuring the quantized values of GQ in two regimes, we determine the edge quantum numbers, which opens a new route for finding the topological order of exotic non-Abelian FQH states.

Kumar, RaviIndian Institute of Science (author)
Spånslätt Rugarn, Christian,1987Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)spanslat (author)
Watanabe, K.National Institute for Materials Science (NIMS) (author)
Taniguchi, T.National Institute for Materials Science (NIMS) (author)
Mirlin, Alexander D.Landau Institute for Theoretical Physics,Karlsruher Institut für Technologie (KIT),Karlsruhe Institute of Technology (KIT) (author)
Gefen, YuvalWeizmann Institute of Science,Karlsruher Institut für Technologie (KIT),Karlsruhe Institute of Technology (KIT) (author)
Das, AnindyaIndian Institute of Science (author)
Indian Institute of ScienceChalmers tekniska högskola (creator_code:org_t)

In:Nature Communications: Springer Science and Business Media LLC13:12041-17232041-1723

By the author/editor: Srivastav, Saura ...; Kumar, Ravi; Spånslätt Rugarn ...; Watanabe, K.; Taniguchi, T.; Mirlin, Alexande ...; show more...; Gefen, Yuval; Das, Anindya; show less...

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NATURAL SCIENCES: NATURAL SCIENCES; and Physical Science ...; and Condensed Matter ...

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