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O: Fachverband Oberflächenphysik
O 45: Ultrafast Electron Dynamics at Surfaces and Interfaces IV
O 45.1: Talk
Wednesday, March 20, 2024, 10:30–10:45, MA 041
Ultrafast Charge Transfer in Graphene/Ag/SiC Studied Using Time- and Angle-Resolved Photoemission Spectroscopy — •Eduard Moos1, Zhi-Yuan Deng1, Hauke Beyer1, Kai Rossnagel1,2,3, and Michael Bauer1,2 — 1Institute of Experimental and Applied Physics, Kiel University, 24098 Kiel, Germany — 2Kiel Nano, Surface and Interface Science KiNSIS, Kiel University, 24118 Kiel, Germany — 3Deutsches ElektronenSynchrotron DESY, Ruprecht Haensel Lab, 22607 Hamburg, Germany
Monoatomic metals intercalated between graphene/SiC interfaces represent a new type of van der Waals heterostructures with extraordinary properties. For instance, silver exhibits a metal-semiconductor transition in the monolayer limit (MLAg) [1, 2]. The low binding energy of the valence band maximum of MLAg, the intrinsic band gap of a bilayer graphene (BLGr) overlayer, and a twisted orientation of the Brillouin zone of silver and graphene overlayer make this heterostructure an interesting model system for the exploration of ultrafast interlayer charge transfer. In this contribution, we use time- and angle-resolved photoemission spectroscopy (TRARPES) with a time resolution of 35 fs to study such types of processes in n-doped BLGr/MLAg/6H-SiC. Following the decay of the photoexcited carriers, we observe clear signatures of a net charge transfer between Ag and graphene on a 50 fs timescale. The detailed analysis of the data allows disentangling and identifying the relevant pathways.
[1] P. Rosenzweig, U. Starke, Phys. Rev. B 101, 201407(R) (2020).
[2] W. Lee et al., Nano Lett. 22, 19, 7841-7847 (2022).
Keywords: Ultrafast; TRARPES; Charge-Transfer; Bilayer-Graphene; Monolayer-Silver