Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 62: Surface Dynamics
O 62.4: Poster
Dienstag, 21. März 2017, 18:30–20:30, P2-OG2
Charge density wave domain growth in 1T-TaS2 mapped by ultrafast LEED — •Theo Diekmann1, Simon Vogelgesang1, Gero Storeck1, Sebastian Schramm1, Max Gulde1, Gerrit Horstmann1, Kai Roßnagel2, Sascha Schäfer1, and Claus Ropers1 — 1IV. Physical Institute - Solids and Nanostructures, University of Göttingen, Germany — 2Institute for Experimental and Applied Physics, University of Kiel, Germany
We developed an ultrafast low-energy electron diffraction (ULEED) setup for the study of time-resolved structural dynamics at surfaces, extending our previous ULEED-experiments operating on ultrathin films in transmission [1]. To this end, a nanoscopic needle emitter is utilized in a miniaturized electrostatic lens geometry as a high-brightness source providing well-collimated electron pulses with a minimal duration of 16 picoseconds at the sample and electron energies in the range of 50-200 eV.
In a first application of this setup, we study the structural phase transition from the room-temperature nearly commensurate (NC) to the incommensurate (IC) charge density wave phase at the surface of 1T-TaS2 [2]. Following intense optical excitation, we observe the formation and consecutive growth of IC domains by a thorough analysis of time-dependent diffraction spot profiles. Our results demonstrate the potential of ULEED for the study of complex ultrafast structural and electronic processes at surfaces.
[1] M. Gulde et al., Science 345, 200 (2014)
[2] K. Haupt et al., Phys. Rev. Lett. 116, 016402 (2016)