Dresden 2020 – scientific programme
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MA: Fachverband Magnetismus
MA 26: Ultrafast Electron Dynamics II (joint session O/MA)
MA 26.4: Talk
Tuesday, March 17, 2020, 11:30–11:45, WIL B321
Visualisation of coherent phonons in Bi2Se3 by time-resolved photoelectron diffraction — •Klara Volckaert1, Davide Curcio1, Dmytro Kutnyakhov2, Steinn Agustsson3, Kevin Bühlmann4, Federico Pressacco2, Michael Heber2, Siarhei Dziarzhytski2, Harald Redin2, Yves Acremann4, Jure Demsar3, Wilfried Wurth2, Charlotte E. Sanders5, and Philip Hofmann1 — 1Aarhus University, Aarhus, Denmark — 2DESY, Hamburg, Germany — 3Johannes Gutenberg-University, Mainz, Germany — 4ETH Zürich, Zürich, Switzerland — 5Rutherford Appleton Laboratories, Harwell, United Kingdom
We have developed X-ray photoelectron diffraction (XPD) as a pump-probe technique allowing for the visualisation of structural changes on femtosecond timescales. We use this new technique to observe the structural dynamics of Bi2Se3 when excited by a 800 nm optical pump pulse. Terahertz oscillations of the fine structure within the resulting XPD pattern were observed, which could originate from the excited A1g coherent phonons. These experiments were carried out at the FLASH free electron laser using a time-of-flight momentum microscope, which allows for simultaneous mapping of the emission angles in addition to kinetic energy of the electrons during a photoemission experiment (see D. Kutnyakhov et al. arXiv:1906.12155 (2019)).