Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Probing the bright exciton state in twisted bilayer graphene via
  resonant Raman scattering   The band structure of bilayer graphene is tunable by introducing a relative
twist angle between the two layers, unlocking exotic phases, such as
superconductor and Mott insulator, and providing a fertile ground for new
physics. At intermediate twist angles around 10{\deg}, highly degenerate
electronic transitions hybridize to form excitonic states, a quite unusual
phenomenon in a metallic system. We probe the bright exciton mode using
resonant Raman scattering measurements to track the evolution of the intensity
of the graphene Raman G peak, corresponding to the E2g phonon. By cryogenically
cooling the sample, we are able to resolve both the incoming and outgoing
resonance in the G peak intensity evolution as a function of excitation energy,
a prominent manifestation of the bright exciton serving as the intermediate
state in the Raman process. For a sample with twist angle 8.6{\deg}, we report
a weakly temperature dependent resonance broadening ${\gamma}$ ${\approx}$ 0.07
eV. In the limit of small inhomogeneous broadening, the observed ${\gamma}$
places a lower bound for the bright exciton scattering lifetime at 10 fs in the
presence of charges and excitons excited by the light pulse for Raman
measurement, limited by the rapid exciton-exciton and exciton-charge scattering
in graphene.

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The categories of this paper are: ao-sci
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The categories of this paper are: stat
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The categories of this paper are: hep-th
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The categories of this paper are: funct-an
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The categories of this paper are: physics
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The categories of this paper are: econ
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-lat
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The categories of this paper are: astro-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
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The categories of this paper are: eess
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The categories of this paper are: plasm-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con