Inelastic X-ray scattering investigations of lattice dynamics in SmFeAsO1−xFysuperconductors

Mathieu Le Tacon (1) , T.R. Forrest (2, 3) , Ch. Rüegg (4) , A. Bosak (5) , J. Noffsinger (3) , A.C. Walters (5) , Pierre Toulemonde (6) , A. Palenzona (7) , N.D. Zhigadlo (8) , J. Karpinski (8) , J.P. Hill (9) , M. Krisch (5) , D.F. Mcmorrow (2)

1 Max-Planck-Institut für Festkörperforschung
2 London Centre for Nanotechnology and Department of Physics and Astronomy
3 Department of Physics [Berkeley]
4 London Centre for Nanotechnology
5 ESRF - European Synchrotron Radiation Facility
6 NEEL - MRS - Matériaux, Rayonnements, Structure
7 NR-INFM-LAMIA
8 Laboratory for Solid State Physics [ETH Zürich]
9 Department of Physics [Upton]

We report measurements of the phonon density of states as probed with inelastic X-ray scattering in SmFeAsO1−xFy powders. An unexpected strong renormalization of phonon branches around 23 meV is observed as fluorine is substituted for oxygen. Phonon dispersion measurements on SmFeAsO1−xFy single crystals allow us to identify the 21 meV A1g in-phase (Sm,As) and the 26 meV B1g (Fe,O) modes to be responsible for this renormalization, and may reveal unusual electron-phonon coupling through the spin channel in iron-based superconductors.

Domaines: Supraconductivité [cond-mat.supr-con]

Mathieu Le Tacon, T.R. Forrest, Ch. Rüegg, A. Bosak, J. Noffsinger, et al.. Inelastic X-ray scattering investigations of lattice dynamics in SmFeAsO1−xFysuperconductors. Journal of Physics and Chemistry of Solids, 2010, 72, pp.523. ⟨10.1016/j.jpcs.2010.10.006⟩. ⟨hal-00987668⟩