SKM 2023 – scientific programme

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SYSD: Symposium SKM Dissertation Prize 2023

SYSD 1: SKM Dissertation Prize

SYSD 1.3: Invited Talk

Monday, March 27, 2023, 10:30–11:00, HSZ 04

Ultrafast Probing and Coherent Vibrational Control of a Surface Structural Phase Transition — •Jan Gerrit Horstmann — Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany — Dept. of Materials, ETH Zürich, Zürich, Switzerland

The desire to exert active optical control over matter is a unifying theme across multiple scientific fields. In femtochemistry, multi-pulse optical excitation schemes exploit coherences in decisive electronic and vibrational degrees of freedom of molecules to influence the efficiencies of chemical reactions. The application of this concept to solid-state systems is, however, complicated by, e.g., the high electronic and vibrational density of states, or couplings to an external heat bath. In this respect, low-dimensional and strongly correlated systems represent a promising intermediate between molecules and bulk solids, with phase transitions assuming the role of a ‘reaction’.

In this talk, I report on the coherent vibrational control of a metal-insulator structural phase transition in a quasi-one-dimensional surface system, namely, atomic indium wires on the (111) surface of silicon. By analogy with repeatedly pushing a child on a swing, we use timed sequences of femtosecond light pulses to manipulate the amplitudes of key phonon modes connecting the insulating and metallic phases, thereby steering the system across the transition state. Our results confirm the applicability of coherent control tactics from femtochemistry to solids, creating not only strong conceptual links between the two fields, but also providing a new handle to switch the chemical and physical functionalities of materials on ultrafast time scales.