Title: Quasiparticle Dynamics and Phonon Softening in FeSe Superconductors
Authors: Luo, C. W.
Wu, I. H.
Cheng, P. C.
Lin, J. -Y.
Wu, K. H.
Uen, T. M.
Juang, J. Y.
Kobayashi, T.
Chareev, D. A.
Volkova, O. S.
Vasiliev, A. N.
Department of Electrophysics
Institute of Physics
Issue Date: 20-Jun-2012
Abstract: Quasiparticle dynamics of FeSe single crystals revealed by dual-color transient reflectivity measurements (Delta R/R) provides unprecedented information on Fe-based superconductors. The amplitude of the fast component in Delta R/R clearly gives a competing scenario between spin fluctuations and superconductivity. Together with the transport measurements, the relaxation time analysis further exhibits anomalous changes at 90 and 230 K. The former manifests a structure phase transition as well as the associated phonon softening. The latter suggests a previously overlooked phase transition or crossover in FeSe. The electron-phonon coupling constant lambda is found to be 0.16, identical to the value of theoretical calculations. Such a small lambda demonstrates an unconventional origin of superconductivity in FeSe.
URI: http://dx.doi.org/257006
ISSN: 0031-9007
DOI: 257006
Volume: 108
Issue: 25
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