Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 16: Poster Monday: Ultrafast Processes 1

O 16.4: Poster

Montag, 5. September 2022, 18:00–20:00, P4

Ultrafast optical spectroscopy of few-layer TMDCs under ultrahigh-vacuum conditions — •Maximilian Franz, Kilian Kuhlbrodt, Jan Gerrit Horstmann, and Claus Ropers — Max-Plank-Institut für Multidisziplinäre Naturwissenschaften, Göttingen, Germany

Optical pump-probe spectroscopy (OPP) has enabled detailed investigations of the nonequilibrium optical properties of atomically thin materials, with prominent examples in graphene or transition metal dichalcogenide (TMDCs) heterostructures [1]. However, these materials are often susceptible to oxidation and contamination under atmospheric conditions, resulting in strongly altered physical and chemical properties [2]. Here, we present the development of an OPP setup for the investigation of dynamics in few-layer TMDCs and heterostructures under ultrahigh vacuum (UHV) conditions. We present first results on the ultrafast phase transition in 1T-TaS₂ samples using time-resolved reflectance and transmittance measurements with fs temporal and µm spatial resolutions. Furthermore, we discuss possible applications, e.g., layer-selective optical excitation of TMDC heterostructures, and the combination of OPP with structure-sensitive techniques like ultrafast low-energy electron diffraction [3].

[1] C. Jin et al., Nature Nanotechnology 13, 994-1003 (2018); [2] Y. Yu et al., Nature Nanotechnology 10, 270-276 (2015); [3] S. Vogelgesang et al., Nature Physics 14, 184-190 (2018)