Dresden 2011 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 15: ISPS Intersectional Poster Session

DY 15.4: Poster

Dienstag, 15. März 2011, 18:00–20:00, P1

Influence of Superconductivity on the Phonon in BaFe_1.8Co_0.2As₂ — •Daniel Lamago^1,2, Lothar Pintschovius¹, Dmitry Reznik³, Rolf Heid¹, and Thomas Wolf¹ — ¹Karslruhe Institut für Technologie (KIT), Institut fuer Festkoerperphysik, P.O.B. 3640, 76021 Karlsruhe, Germany — ²Laboratoire Leon Brillouin, CEA Saclay, 91191 Gif sur Yvette Cedex, France — ³Department of Physics, University of Colorado-Boulder, CO 80309 Boulder, USA

We used inelastic neutron scattering technique to investigate the role of electron-phonon coupling in the mechanism of high-Tc superconductivity in the iron arsenides. Density functional theory predicts only a weak electron-phonon coupling but theory might underestimate the coupling strength. One way to obtain experimantally information on the electron-phonon coupling strength is to measure superconductivity-induced phonon frequency shifts. Such shifts have been observed not only in conventional superconductors but also in cuprates, i.e. in compounds in which electron-phonon coupling is probably not the main driving mechanism for superconductivity. We have measured phonon modes with an energy close to the superconducting energy gap, because it is known from theory that such phonons will respond most strongly to the opening of the superconducting gap. The gap energy was estimated to be about 6 meV for the overdoped sample and about 8 meV for the optimally doped one. We could not detect any influence of superconductivity on the phonons, neither on the linewidth nor on the frequencies.