Ghosh, A and Chakraborty, S and Ghorai, U and Paul, AK and Watanabe, K and Taniguchi, T and Sensarma, R and Das, A (2023) Evidence of compensated semimetal with electronic correlations at charge neutrality of twisted double bilayer graphene. In: Communications Physics, 6 (1).
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Abstract
Recently, magic-angle twisted bilayer graphene (MATBLG) has emerged with various interaction-driven novel quantum phases at the commensurate fillings of the moiré superlattice, while the charge neutrality point (CNP) remains mostly a trivial insulator. Here, we show an emerging phase of compensated semimetallicity at the CNP of twisted double bilayer graphene (TDBLG), a close cousin of MATBLG, with signatures of electronic correlation. Using electrical and thermal transport, we find two orders of magnitude enhancement of the thermopower at magnetic fields much smaller than the extreme quantum limit, accompanied by large magnetoresistance (~ 2500) at CNP, providing strong experimental evidence of compensated semimetallicity at CNP of TDBLG. Moreover, at low temperatures, we observe unusual sublinear temperature dependence of resistance. A recent theory1 predicts the formation of an excitonic metal near CNP, where small electron and hole pockets co-exist. We understand this sublinear temperature dependence in terms of critical fluctuations in this theory. © 2023, The Author(s).
| Item Type: | Journal Article |
|---|---|
| Publication: | Communications Physics |
| Publisher: | Nature Research |
| Additional Information: | The copyright for this article belongs to authors. |
| Keywords: | Quantum chemistry; Temperature distribution, Bilayer Graphene; Charge neutrality; Commensurate filling; Electronic correlation; Magic angle; Neutrality point; Quantum phase; Sublinear; Temperature dependence; Twisted bilayers, Graphene |
| Department/Centre: | Division of Physical & Mathematical Sciences > Physics |
| Date Deposited: | 16 Nov 2024 15:57 |
| Last Modified: | 16 Nov 2024 15:57 |
| URI: | http://eprints.iisc.ac.in/id/eprint/85323 |
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