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HL: Fachverband Halbleiterphysik

HL 85: Poster Session II

HL 85.24: Poster

Donnerstag, 17. März 2011, 18:00–21:00, P4

Ultrafast X-Ray Diffraction on a STO/SRO Superlattice — •Daniel Schick¹, Marc Herzog¹, Clemens von Korff Schmising², Peter Gaal¹, and Matias Bargheer¹ — ¹Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany — ²Atomic Physics Division, Department of Physics, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden

Ultrafast x-ray diffraction is capable of probing atomic motions on the fs-timescale. With the new laser-driven table-top plasma x-ray source at the University of Potsdam we are able to generate ≈ 100 fs pulses of Cu K_α radiation with a repetition rate of 1 kHz and a total flux of 5×10⁵ ph/s on the sample.

Here we compare ultrafast optical reflectivity changes and ultrafast x-ray diffraction data of a SrTiO₃/SrRuO₃ superlattice (SL) in order to highlight the relative phase of oscillations in all-optical pump-probe data to the phase of the atomic motion. For high pump fluences we observed for the first time that on longer time scales (15 ps) the Bragg-peaks not only shift due to the lattice expansion but rather split into two separate Bragg-peaks, which can accurately be predicted by simulations of the phonon dynamics in a linear chain model and dynamical x-ray diffraction theory.