Regensburg 2025 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 26: Focus Session Ultrafast Electron Microscopy at the Space-Time Limit III
O 26.8: Vortrag
Dienstag, 18. März 2025, 12:30–12:45, H2
Ultrafast Electron Diffraction and Microscopy of Structural Phase Transitions at Megahertz Rates — •Till Domröse1,2 and Claus Ropers1,2 — 1Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany — 24th Physical Institute, University of Göttingen, Germany
Control over laser-induced structural phase transformations promises tuning of macroscopic materials properties on femtosecond timescales. Ultrafast electron diffraction (UED) elucidates the spatially averaged evolution of lattice symmetries and phonon populations during the transitions. However, resolving nanoscale structural heterogeneity in these measurements remains challenging due to the reduced brightness of pulsed electron beams. Here, we overcome fundamental limitations in the stroboscopic investigation of structural dynamics in thin material films by UED and ultrafast electron microscopy. A high-coherence electron source offers enhanced momentum resolution in collimated electron nanobeams, while thermally-optimized sample supports enable reversible driving of structural transitions at high duty cycles [1]. Utilizing the associated gain in coherent electron current, we conduct nano-UED investigations of charge-density wave dynamics in layered materials, tomographically reconstructing three-dimensional phase formation kinetics in 1T-TaS2 [2], and revealing a femtosecond structural quench in 1T’-TaTe2 cycled at a repetition rate of 2 MHz [3].
[1] T. Domröse, et al., arXiv:2410.02310 (2024)
[2] T. Domröse, et al., Nature Materials 22(11) (2023)
[3] T. Domröse, C. Ropers, Physical Review B 110(8) (2024)
Keywords: Ultrafast electron diffraction; Structural phase transitions; Charge-density waves; Ultrafast Transmission Electron Microscopy; Two-dimensional materials