SKM 2023 – scientific programme
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O: Fachverband Oberflächenphysik
O 19: Poster: Ultrafast Electron Dynamics at Surface and Interfaces I
O 19.8: Poster
Monday, March 27, 2023, 18:00–20:00, P2/EG
Spin- and valley-dependent charge carrier dynamics in a WSe2 bulk crystal — •Gregor Zinke1, Sebastian Hedwig1, Benito Arnoldi1, Martin Aeschlimann1, and Benjamin Stadtmüller1,2 — 1Department of Physics and Research Center OPTIMAS, TU Kaiserslautern, 67663 Kaiserslautern, Germany — 2Institute of Physics, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
The intriguing spin functionalities of transition metal dichalcogenides such as WSe2 are rooted in the spin- and valley-degrees of freedom. These are responsible for the particular spin-texture of TMDCs as well as the helicity- and valley-dependent light absorption. However, despite the clear understanding of the initial spin-and valley-dependent light-matter interaction, a clear picture of the spin-dependent intra- and intervalley scattering of electrons and holes is still elusive. Here, we focus on the ultrafast carrier dynamics in a bulk crystal of WSe2. Using spin-, time- and angle-resolved photoemission with XUV-radiation, we simultaneously image the temporal evolution of the excited carriers in the conduction band as well as the corresponding hole dynamics within the valence band on a fs timescale. The spin-polarization of the initially excited carriers is controlled by the helicity of the optical excitation. We will show clear changes of the spin-polarization of the excited electrons after intra-band scattering from the K- to the Σ-point, and discuss these results in regards to the influence of electron-electron and electron-phonon scattering for the spin-polarized electron population in the conduction band.