Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 27: Superconductivity: Fe-based Superconductors - 122
TT 27.10: Vortrag
Dienstag, 12. März 2013, 12:15–12:30, H18
Coherent phonon oscillations in 122 FeAs compounds — •L. Rettig1, R. Cortes2, T. Rohwer3, P. Gegenwart4, H.S. Jevaan4, T. Wolf5, B. Kamble6, I. Eremin6, L. Kipp3, K. Rossnagel3, M. Bauer3, J. Fink7, M. Wolf2, and U. Bovensiepen1 — 1Universität Duisburg-Essen, D-47048 Duisburg — 2Fritz-Haber-Institut d. MPG, D-14195 Berlin — 3Christian-Albrechts-Universität Kiel, D-24118 Kiel — 4Georg-August-Universität Göttingen, D-37077 Göttingen — 5Karlsruhe Institute of Technology, D-76021 Karlsruhe — 6Ruhr-Universität Bochum, D-44801 Bochum — 7Leibniz-Institute for Solid State and Materials Research Dresden, D-01171 Dresden
We present time- and angle-resolved photoemission spectroscopy results on various 122 FeAs compounds employing fs UV and XUV pulses. We observe coherent oscillations of the spectral weight near EF and identify three coherent modes - the most prominent Raman active A1g mode and two weaker modes. The analysis of the transient electron distribution allow us to separate the oscillating chemical potential from the relaxation dynamics of the excited electronic distribution.
Similar experiments using a high-harmonics light source enable the analysis of the electron dynamics at the Γ-point and at the X-point, which shows an in-phase oscillation of the chemical potential at the two Fermi surface sheets. This indicates a substantial modification of the electronic density of states by the coherent oscillations, which is corroborated by theoretical investigations of the influence of the A1g mode on the electronic structure in 122 FeAs compounds.