Interaction driven giant thermopower in magic-angle twisted bilayer graphene
ORAL
Abstract
Magic-angle twisted bilayer graphene (MtBLG) has proven to be an extremely promising new platform
to realize and study a host of emergent quantum phases arising from the strong correlations in
its narrow bandwidth flat band. In this regard, thermal transport phenomena like thermopower, in
addition to being coveted technologically, is also sensitive to the particle-hole (PH) asymmetry, making
it a crucial tool to probe the underlying electronic structure of this material. We have carried
out thermopower measurements of MtBLG as a function of carrier density, temperature and magnetic
field, and report the observation of an unusually large thermopower reaching up to a value as
high as ~100μV/K at a low temperature of 1K. Surprisingly, our observed thermopower exhibits
peak-like features in close correspondence to the resistance peaks around the integer Moire fillings,
including the Dirac Point, violates the Mott formula. We show that the large thermopower peaks and
their associated behaviour arise from the emergent highly PH asymmetric electronic structure due to
the cascade of Dirac revivals. Furthermore, the thermopower shows an anomalous peak around the
superconducting transition on the hole side and points towards the possible role of enhanced superconducting
fluctuations in MtBLG.
to realize and study a host of emergent quantum phases arising from the strong correlations in
its narrow bandwidth flat band. In this regard, thermal transport phenomena like thermopower, in
addition to being coveted technologically, is also sensitive to the particle-hole (PH) asymmetry, making
it a crucial tool to probe the underlying electronic structure of this material. We have carried
out thermopower measurements of MtBLG as a function of carrier density, temperature and magnetic
field, and report the observation of an unusually large thermopower reaching up to a value as
high as ~100μV/K at a low temperature of 1K. Surprisingly, our observed thermopower exhibits
peak-like features in close correspondence to the resistance peaks around the integer Moire fillings,
including the Dirac Point, violates the Mott formula. We show that the large thermopower peaks and
their associated behaviour arise from the emergent highly PH asymmetric electronic structure due to
the cascade of Dirac revivals. Furthermore, the thermopower shows an anomalous peak around the
superconducting transition on the hole side and points towards the possible role of enhanced superconducting
fluctuations in MtBLG.
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Presenters
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Anindya Das
- Indian Institute of Science Bangalore