Regensburg 2022 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 36: Focus Session: Ultrafast Spin, Lattice and Charge Dynamics of Solids

TT 36.1: Hauptvortrag

Freitag, 9. September 2022, 09:30–10:00, H10

Coherent control of lattice and electronic states — •Steven Johnson — ETH Zurich, Zurich, Switzerland — Paul Scherrer Institut, Villigen, Switzerland

In this presentation I discuss a selection of recent efforts to use ultrafast light pulse excitation ranging from near-infrared to THz wavelengths to achieve control over both structural and electronic degrees of freedom in condensed phase materials. In one example, ultrafast excitation of a quasi-2D material results in a large-scale coherent modulation of structure (as seen by femtosecond x-ray diffraction) and associated carrier effective masses. These modulations are strongly connected to a nearby topological phase transition. In another example I discuss experiments uisiing high field THz pulses to drive both coherent and incoherent carrier dynamics in a narrow-gap semiconductor, and describe how these dynamics can be inferred from multidimensional THz spectroscopy. The results demonstrate that carrier multiplication effects become dominant at moderately intense field strengths. In the final example I will discuss ongoing efforts to use combinations of high- and low-frequency light excitation to drive nonlinear structural dynamics in a soft mode ferroelectric.