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Interaction-driven giant thermopower in magic-angle twisted bilayer graphene

Paul, AK and Ghosh, A and Chakraborty, S and Roy, U and Dutta, R and Watanabe, K and Taniguchi, T and Panda, A and Agarwala, A and Mukerjee, S and Banerjee, S and Das, A (2022) Interaction-driven giant thermopower in magic-angle twisted bilayer graphene. In: Nature Physics .

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Official URL: https://doi.org/10.1038/s41567-022-01574-3


Magic-angle twisted bilayer graphene has proved to be a fascinating platform to realize and study emergent quantum phases arising from the strong correlations in its flat bands. Thermal transport phenomena, such as thermopower, are sensitive to the particle�hole asymmetry, making them a crucial tool to probe the underlying electronic structure of this material. Here we have carried out thermopower measurements of magic-angle twisted bilayer graphene as a function of carrier density, temperature and magnetic field. We report the observation of an unusually large thermopower reaching a value of the order of 100 μV K�1 at a low temperature of 1 K. The thermopower exhibits peak-like features that violate the Mott formula in close correspondence to the resistance peaks appearing around the integer filling of the moiré bands, including the Dirac point. We show that the large thermopower peaks and their associated behaviour arise from the emergent highly particle�hole-asymmetric electronic structure, due to the sequential filling of the moiré flat bands and the associated recovery of Dirac-like physics. Furthermore, the thermopower shows an anomalous peak around the superconducting transition, which points towards the possible role of superconducting fluctuations in magic-angle twisted bilayer graphene. © 2022, The Author(s), under exclusive licence to Springer Nature Limited.

Item Type: Journal Article
Publication: Nature Physics
Publisher: Nature Research
Additional Information: The copyright for this article belongs to Authors
Keywords: Graphene; Temperature; Thermoelectric power, Bilayer Graphene; Electronic.structure; Flat band; Magic angle; Particle-hole asymmetry; Quantum phase; Strong correlation; Thermal transport; Transport phenomenon; Twisted bilayers, Electronic structure
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 19 May 2022 05:21
Last Modified: 19 May 2022 05:21
URI: https://eprints.iisc.ac.in/id/eprint/72060

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