SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 54: Poster Session IV: Poster to Mini-Symposium: Ultrafast surface dynamics at the space-time limit II
O 54.1: Poster
Dienstag, 2. März 2021, 13:30–15:30, P
Ultrafast nano-imaging of the order parameter in a structural phase transition — •Till Domröse1, Thomas Danz1, and Claus Ropers1,2 — 14th Physical Institute - Solids and Nanostructures, University of Göttingen, Germany — 2Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
Ultrafast transmission electron microscopy has proven a versatile tool to investigate out-of-equilibrium dynamics in heterogeneous nanostructures on their intrinsic time and length scales [1]. Here, we report on ultrafast dark-field domain mapping in our Göttingen UTEM [2] as a means to image a structural phase transition between two charge density wave (CDW) phases in the correlated material 1T-TaS2 [3]. Selective contrast enhancement enabled by a tailored dark-field aperture array provides real-space sensitivity to the local CDW amplitude with unprecedented simultaneous femtosecond temporal and nanometer spatial resolution. After optical excitation, we observe a global quench of the CDW amplitude, followed by formation, condensation and subsequent spatiotemporal relaxation of domain patterns, ranging from the femtosecond into the nanosecond regime. Accompanying Ginzburg-Landau simulations reproduce key experimental observations, elucidating the order parameter dynamics specifically near domain walls.
[1] A. H. Zewail, Science 328, 187 (2010).
[2] A. Feist et al., Ultramicroscopy 176, 63 (2017).
[3] T. Danz et al., accepted for publication in Science, arXiv:2007.07574