SurfaceScience21 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 3: Mini-Symposium: Ultrafast surface dynamics at the space-time limit I

O 3.3: Hauptvortrag

Montag, 1. März 2021, 11:15–11:45, R1

Ultrafast structural phase transitions probed by low-energy electron diffraction — •Claus Ropers — IV. Phys. Inst., Göttingen, Germany — MPI for biophysical Chemistry

Governed by broken symmetries and an effectively reduced dimensionality, surfaces exhibit a multitude of complex phases and transitions, with prominent examples in metal-to-insulator lattice instabilities. Ultrafast measurement technology has greatly improved our understanding of the formation and non-equilibrium response of such phases, revealing transition pathways and means of optical control.

Despite these advancements, tracking the rapid structural evolution of surfaces has remained challenging. Low-energy electron diffraction (LEED) is an ideal tool to characterize the structure, symmetries and long-range order at surfaces, but it typically lacks ultrafast temporal resolution.

This talk will present the development and first applications of Ultrafast LEED, combining short-pulsed probing with ultimate surface sensitivity. I will give some methodical background on its implementation and will discuss results on optically induced structural phase transitions in charge-density wave systems [1,2].

[1] "Structural dynamics of incommensurate charge-density waves tracked by ultrafast low-energy electron diffraction" G. Storeck et al., Struct. Dyn. 7, 034304 (2020).

[2] "Coherent control of a surface structural phase transition", J.G. Horstmann et al., Nature 583, 232 (2020).