Direct view of exciton and carrier dynamics in twisted bilayer graphene
Abstract
Twisted bilayer graphene (tBLG) on H-intercalated SiC (twist angle of 9 ± 1∘) is studied by position\mbox{-}, time\mbox{-}, and angle-resolved photoemission spectroscopy (ARPES). Both graphene layers are hole doped, with a Dirac-point offset of 30~meV. Time-resolved ARPES near the van Hove singularity reveals a spectral feature within the hybridization-induced band gap, together with excited electrons in the conduction band. The in-gap feature exhibits distinct dynamics, and its binding energy and k-space location are consistent with the proposed non-hydrogenic ``ghost-Fano'' exciton arising from destructive interference between two nearly degenerate excitonic channels. Near the Dirac points, the twist separates the largely layer-polarized Dirac cones in momentum space, providing direct layer selectivity. We find markedly different peak electronic temperatures in the two graphene layers, even though their subsequent cooling dynamics are very similar. We attribute this to an ultrafast interlayer redistribution of electronic energy, driven by an interlayer electric field that arises from the different doping in the layers.
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BibTeX
@misc{gatti2026direct,
title = {{Direct view of exciton and carrier dynamics in twisted bilayer graphene}},
author = {Gianmarco Gatti and Anders S. Mortensen and Zhihao Jiang and Alfred J. H. Jones and Gesa-R. Siemann and Thomas S. Nielsen and Søren Ulstrup and Naina Kushwaha and Bruce Weaver and Yu Zhang and Emma Springate and Charlotte E. Sanders and Vibha Reddy and Ulrich Starke and Philip Hofmann},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.17984},
eprint = {2610.17984},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.17984},
}
RIS
TY - UNPB
TI - Direct view of exciton and carrier dynamics in twisted bilayer graphene
AU - Gianmarco Gatti
AU - Anders S. Mortensen
AU - Zhihao Jiang
AU - Alfred J. H. Jones
AU - Gesa-R. Siemann
AU - Thomas S. Nielsen
AU - Søren Ulstrup
AU - Naina Kushwaha
AU - Bruce Weaver
AU - Yu Zhang
AU - Emma Springate
AU - Charlotte E. Sanders
AU - Vibha Reddy
AU - Ulrich Starke
AU - Philip Hofmann
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2610.17984
UR - https://arxiv.org/abs/2610.17984
AB - Twisted bilayer graphene (tBLG) on H-intercalated SiC (twist angle of 9 ± 1^∘) is studied by position\mbox{-}, time\mbox{-}, and angle-resolved photoemission spectroscopy (ARPES). Both graphene layers are hole doped, with a Dirac-point offset of 30~meV. Time-resolved ARPES near the van Hove singularity reveals a spectral feature within the hybridization-induced band gap, together with excited electrons in the conduction band. The in-gap feature exhibits distinct dynamics, and its binding energy and k-space location are consistent with the proposed non-hydrogenic ``ghost-Fano'' exciton arising from destructive interference between two nearly degenerate excitonic channels. Near the Dirac points, the twist separates the largely layer-polarized Dirac cones in momentum space, providing direct layer selectivity. We find markedly different peak electronic temperatures in the two graphene layers, even though their subsequent cooling dynamics are very similar. We attribute this to an ultrafast interlayer redistribution of electronic energy, driven by an interlayer electric field that arises from the different doping in the layers.
ER -