Dresden 2026 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 66: Ultrafast electron dynamics at surface and interfaces III
O 66.2: Vortrag
Mittwoch, 11. März 2026, 15:30–15:45, TRE/MATH
Ultrafast signatures of Dirac - flat-band hybrid states from time-resolved ARPES — •Maria-Elisabeth Federl1, Johannes Gradl1, Franziska Bergmeier1, Zamin Mamiyev2, Niclas Tilgner2, Thomas Seyller2, Christoph Tegenkamp2, and Isabella Gierz1 — 1University of Regensburg — 2Chemnitz University of Technology
Hybridization of highly itinerant Dirac electrons with localized flat-band states is predicted to yield emergent phenomena such as exotic heavy-fermion behaviour. Epitaxial graphene resting on a flat-band system at the graphene-SiC(0001) interface offers a promising platform, yet direct spectroscopic signatures - such as avoided crossings in equilibrium ARPES - have remained unresolved. We solved this problem using time-resolved ARPES where evidence of hybridization manifested in three key observations: (1) accelerated Dirac-carrier relaxation due to an increased scattering phase space, (2) transient charging of the Dirac cone enabled by direct optical excitation from the flat bands, and (3) ultrafast charge transfer back into the flat bands on timescales set by the interlayer coupling strength. Our results thus provide a clear dynamical fingerprint of hybridization in a system where equilibrium probes have proven inconclusive.
Keywords: trARPES; graphene/flat-band system; interlayer hybridization; confinement heteroepitaxy