Quasiparticle dynamics and phonon softening in FeSe superconductors

Chih-Wei Luo*, I. H. Wu, P. C. Cheng, Jiunn-Yuan Lin, Kaung-Hsiung Wu, T. M. Uen, Jenh-Yih Juang, T. Kobayashi, D. A. Chareev, O. S. Volkova, A. N. Vasiliev

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


Quasiparticle dynamics of FeSe single crystals revealed by dual-color transient reflectivity measurements (ΔR/R) provides unprecedented information on Fe-based superconductors. The amplitude of the fast component in ΔR/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 λ is found to be 0.16, identical to the value of theoretical calculations. Such a small λ demonstrates an unconventional origin of superconductivity in FeSe.

Original languageEnglish
Article number257006
Number of pages5
JournalPhysical Review Letters
Issue number25
StatePublished - 20 Jun 2012


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