Dresden 2026 – scientific programme
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O: Fachverband Oberflächenphysik
O 98: Ultrafast electron dynamics at surface and interfaces IV
O 98.2: Talk
Friday, March 13, 2026, 10:00–10:15, TRE/MATH
Coherent phonon control beyond amplitude saturation in a sliding ferroelectric — •Jan Gerrit Horstmann1,2, Christoph Emeis3, Andrin Caviezel1, Quintin Meier4, Nicolas Wyler1, Thomas Lottermoser1, Fabio Caruso3, and Manfred Fiebig1 — 1Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, Zurich, 8093, Switzerland — 2University of Würzburg, Institute of Physical and Theoretical Chemistry, Am Hubland, 97074 Würzburg, Germany — 3Institute of Theoretical Physics and Astrophysics, Kiel University, Leibnizstraße 15, Kiel, 24118, Germany — 4Institut Néel, C.N.R.S-Université Grenoble Alpes, BP 166, Grenoble, 38042, France
Intense optical excitation can drive quantum materials into regimes where the usual linear relation between photo-excited carriers and lattice-driving forces no longer applies. Using time-resolved second-harmonic generation, we observe that the interlayer sliding phonon governing sliding ferroelectricity in WTe2 saturates and even decreases at high single-pulse fluence. Density functional theory traces this nonlinearity to band-specific electron-phonon coupling that produces competing lattice forces. By dividing the same total fluence into two well-timed pulses, we avoid populating counteracting electronic states and achieve significantly larger coherent phonon amplitudes. The resulting enhanced sliding motion reveals anharmonic phonon coupling far from equilibrium and shows that nonlinear limits in driven solids can be overcome through temporal shaping of the optical excitation.
Keywords: Coherent phonons; Sliding ferroelectrics; Second harmonic generation; Structural dynamics