Regensburg 2022 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 15: Nano- and Optomechanics
TT 15.3: Talk
Tuesday, September 6, 2022, 11:45–12:00, H23
Generation of coherent acoustic phonons at the atomic scale with femtosecond Coulomb forces — •Shaoxiang Sheng1, Anne-Catherine Oeter1, Mohamad Abdo1, Kurt Lichtenberg1, Mario Hentschel3, and Sebastian Loth1,2 — 1University of Stuttgart, Institute for Functional Matter and Quantum Technologies, Stuttgart, Germany — 2Max Planck Institute for Solid State Research, Stuttgart, Germany — 3University of Stuttgart, 4th Physics Institute, Stuttgart, Germany
Coherent acoustic phonons enable ultrafast control of solids and have been exploited for applications in various acoustic devices. We find that localized coherent acoustic phonon wavepackets can be launched by THz-induced ultrafast Coulomb forces in a scanning tunneling microscope (STM) junction. The wavepackets induce an ultrafast displacement of the surface with several picometers amplitude and propagate into the sample with low losses. The surface displacement can be precisely controlled by varying the tip-sample distance. This non-thermal femtosecond force excitation enables localized measurements of phonon propagation with nanometer spatial resolution, can be used for diagnostics below surfaces and opens new perspectives in exploiting coherent phonons at the atomic scale.