Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 63: Poster DS (joint session DS/MM/O)
O 63.21: Poster
Wednesday, March 20, 2024, 17:00–19:00, Poster B
Ultrafast Lattice Dynamics in Epitaxially Grown Bismuth Thin Films — •Timo Veslin1, Felix Hoff1, Jonathan Frank1, Abdur Rehman Jalil3, Julian Mertens1, and Matthias Wuttig1,2,3 — 1I.Institute of Physics (IA) RWTH Aachen University — 2Jülich-Aachen Research Alliance (JARA FIT and JARA HPC) — 3PGI 10 (Green IT), Forschungszentrum Jülich GmbH
Femtosecond optical pump probe measurements are carried out in order to detect changes in the reflectivity of the material response of epitaxially grown bismuth thin films on sub-ps timescales. Examination of reflectivity changes due to the coherent phonon response provides insight into the ultrafast lattice dynamics and relaxation of bismuth thin films. The pronounced thickness dependent behavior of bismuth is analysed by coherent phonons within the framework of displacive and impulsive excitation models. Here, we show how the competition of phonon softening due to different laser fluencies and phonon hardening from confinement effects can be understood. Raman measurements are carried out to help to disentangle both effects. XRD measurements are shown to help to understand the structural change of the lattice structure. These combined measurements will help to understand confinement and fluency effects in a single model and shows how to tune bonding properties in this unconventional class of materials.
Keywords: Pump Probe; Ultra-thin Bismuth Films; Coherent Phonons; Femtosecond Laser; Confinement Effects