Regensburg 2022 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 30: Poster 2
HL 30.49: Poster
Thursday, September 8, 2022, 11:00–13:00, P3
Coherent acoustic phonons in a Graphite-hBN heterostructure observed by ultrafast electron diffraction — •Arne Ungeheuer1, Nora Bach2, Ahmed Hassanien1, Mashood Mir1, Lukas Nöding1, Sascha Schäfer2, Thomas Baumert1, and Arne Senftleben1 — 1University of Kassel, Institute of Physics, Kassel, Germany — 2University of Oldenburg, Institute of Physics, Oldenburg, Germany
We investigate the dynamics of photoexcited coherent acoustic phonon modes in a graphite- hexagonal boron nitride (hBN) heterostructure. Since the hBN layer is transparent at our excitation central wavelength of 785 nm we assume that the optically induced stress pulse occurs mainly in the graphite layer. Subsequent lattice coupling to the hBN layer depends on the coupling strength at the bilayer interface and determines the nanomechanical resonance frequencies of the system. Observation of specific coherent acoustic phonon modes in the individual layers is interpreted within the framework of ultrafast electron diffraction [1] and experimental results are compared with numerical simulations based on a discrete numerical linear chain model [2].
[1] Gerbig, C., et al. New Journal of Physics 17.4 (2015): 043050. [2] Bach, N., and S. Schäfer, Structural Dynamics 8.3 (2021): 035101.