SKM 2023 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 83: Focus Session: Ultrafast Dynamics in Nanostructures II
O 83.8: Vortrag
Donnerstag, 30. März 2023, 17:15–17:30, GER 38
Light-induced hexatic state in a layered quantum material — •Till Domröse1, Thomas Danz1, Sophie F. Schaible2, Kai Rossnagel3,4, Sergey V. Yalunin1, and Claus Ropers1,2 — 1Max Planck Institute for Multidiscipinary Sciences, Göttingen, Germany — 24th Physical Institute, University of Göttingen, Germany — 3Institute of Experimental and Applied Physics, Kiel University, Germany — 4Ruprecht Haensel Laboratory, DESY, Hamburg, Germany
Ultrafast transmission electron microscopy (UTEM) is a powerful technique for resolving non-equilibrium dynamics on the nanoscale, employing a stroboscopic laser pump/electron probe approach [1]. Here, we harness the high-coherence electron source of the Göttingen UTEM [2] in the investigation of a structural phase transition between two charge-density wave (CDW) phases in a layered material [3]. A three-dimensional reconstruction of the nascent CDW order by means of ultrafast tilt-series nanobeam diffraction allows us to identify a transient hexatic state in the early stages of the phase formation. As the optical excitation induces a loss of interlayer correlations, this two-dimensional intermediate is characterized by a high density of topological defects suppressing the translational symmetry, while the orientational order is weakly preserved. On longer timescales, defect recombination and the establishment of the equilibrium stacking sequence lead to the formation of the long-range ordered high-temperature CDW phase.
[1] A. H. Zewail, Science 328, 187-193 (2010).
[2] A. Feist et al., Ultramicroscopy 176, 63-73 (2017).
[3] T. Domröse et al., in Review, arXiv:2207.05571 [cond-mat.mtrl-sci]