Ultrafast dynamics and phonon softening in Fe1+ySe 1-xTex single crystals

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

*Corresponding author for this work

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The ultrafast quasiparticle dynamics of Fe1+ySe 1-xTex single crystals were investigated by dual-color transient reflectivity measurements (ΔR/R) from 4.3 to 290 K. The electron-phonon coupling strength λ (= 0.16-0.01) and the temperature-dependent energy of longitudinal-acoustic phonons were, respectively, obtained from the relaxation time of a fast component and the period of an oscillation component in ΔR/R. Such a small λ demonstrates the unconventional origin of superconductivity in FeSe. Moreover, the temperature-dependent ΔR/R exhibits anomalous changes at T c, 90 K and 230 K, unambiguously revealing the phase transition as well as the phonon softening via the magnetoelastic effect.

Original languageEnglish
Article number103053
Number of pages14
JournalNew Journal of Physics
StatePublished - 1 Oct 2012


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