Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 23: Poster Ultrafast Electron Dynamics

O 23.4: Poster

Montag, 17. März 2025, 18:00–20:00, P2

Ultrafast Charge Transfer and Band Renormalization in Bilayer Graphene/single layer Ag/SiC — •Eduard Moos¹, Zhi- Yuan Deng¹, Hauke Beyer¹, Arpit Jain⁴, Chengye Dong⁴, Joshua A. Robinson⁴, Kai Rossnagel^1,2,3, and Michael Bauer^1,2 — ¹Kiel University, Germany — ²Kiel Nano, Surface and Interface Science KiNSIS, Germany — ³Electron Synchrotron DESY, Germany — ⁴Pennsylvania State University, United States

Intercalated monoelement metals between mono- to multi-layer graphene/SiC interfaces are a new type of van der Waals heterostructures with extraordinary properties. In the monolayer limit, silver (MLAg) exhibits a metal-semiconductor transition and enables ultrafast charge transfer between layers. Due to the twisted arrangement of the Brillouin zones, low binding energy of the valence band maximum of MLAg and the resulting band gap of bilayer graphene (BLGr), this is an interesting model system to investigate charge transfer and interlayer coupling mechanisms.

In this contribution, time- and angle-resolved photoemission spectroscopy (TRARPES) with a time resolution of 35 fs is used. The data show clear evidence for a net charge transfer between Ag and graphene on a time scale of 50 fs. On longer time scales, the electronic structure of BLGr undergoes significant changes, including an enhancement of the intrinsic splitting of the pi band as well as a reduction of the band gap. We associate these with changes in the electronic and/or structural symmetry of BLGr.

Keywords: Ultrafast; TRARPES; Heterostructure; Graphene; Silver