SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 75: Focus Session: Ultrafast Dynamics in Nanostructures I
O 75.8: Vortrag
Donnerstag, 30. März 2023, 12:45–13:00, GER 38
Mode-selective ballistic pathway to a metastable electronic phase — •Hannes Böckmann1,2, Jan Gerrit Horstmann3, Felix Kurtz1,2, Abdus Samad Razzaq4, Stefan Wippermann4, and Claus Ropers1,2 — 1Max Planck Institute for Multidisciplinary Sciences, Göttingen 37077, Germany — 24th Physical Institute, Solids and Nanostructures, University of Göttingen — 3Department of Materials, ETH Zurich, Zurich — 4Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf
Exploiting vibrational excitation for the dynamic control of material properties is an attractive goal with wide-ranging technological potential. Most metal-to-insulator transitions are mediated by few structural modes and are, thus, ideal candidates for selective driving toward a desired electronic phase. Such targeted navigation within a generally multi-dimensional potential energy landscape requires microscopic insight into the non-equilibrium pathway. However, the exact role of coherent inertial motion across the transition state has remained elusive. Here, we demonstrate mode-selective control over the metal-to-insulator phase transition of atomic indium wires on the Si(111) surface, monitored by ultrafast low-energy electron diffraction. We use tailored pulse sequences and spectrally selective excitation to individually enhance or suppress key phonon modes and thereby steer the collective atomic motion within the potential energy surface underlying the structural transformation. Our work illustrates that coherent excitation of collective modes via exciton-phonon interactions evades entropic barriers and enables the dynamic control of functionality.