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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Abstract

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
Volume14
DOIs
StatePublished - 1 Oct 2012

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