Ultrafast dynamics and phonon softening in Fe1+ySe1−xTex single crystals

C W Luo; I H Wu; P C Cheng; J-Y Lin; K H Wu; T M Uen; J Y Juang; T Kobayashi; Y C Wen; T W Huang; K W Yeh; M K Wu; D A Chareev; O S Volkova; A N Vasiliev

doi:10.1088/1367-2630/14/10/103053

New Journal of Physics (Jan 2012)

Ultrafast dynamics and phonon softening in Fe1+ySe1−xTex single crystals

C W Luo,
I H Wu,
P C Cheng,
J-Y Lin,
K H Wu,
T M Uen,
J Y Juang,
T Kobayashi,
Y C Wen,
T W Huang,
K W Yeh,
M K Wu,
D A Chareev,
O S Volkova,
A N Vasiliev

Affiliations

C W Luo: Department of Electrophysics, National Chiao Tung University , Hsinchu 300, Taiwan
I H Wu: Department of Electrophysics, National Chiao Tung University , Hsinchu 300, Taiwan
P C Cheng: Department of Electrophysics, National Chiao Tung University , Hsinchu 300, Taiwan
J-Y Lin: Institute of Physics, National Chiao Tung University , Hsinchu 300, Taiwan
K H Wu: Department of Electrophysics, National Chiao Tung University , Hsinchu 300, Taiwan
T M Uen: Department of Electrophysics, National Chiao Tung University , Hsinchu 300, Taiwan
J Y Juang: Department of Electrophysics, National Chiao Tung University , Hsinchu 300, Taiwan
T Kobayashi: Department of Electrophysics, National Chiao Tung University , Hsinchu 300, Taiwan; Advanced Ultrafast Laser Research Center and Department of Engineering Science, Faculty of Informatics and Engineering, The University of Electro-Communications , 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
Y C Wen: Institute of Physics , Academia Sinica, Taipei 115, Taiwan
T W Huang: Institute of Physics , Academia Sinica, Taipei 115, Taiwan
K W Yeh: Institute of Physics , Academia Sinica, Taipei 115, Taiwan
M K Wu: Institute of Physics , Academia Sinica, Taipei 115, Taiwan
D A Chareev: Institute of Experimental Mineralogy , Chernogolovka, Moscow Region 142432, Russia
O S Volkova: Low Temperature Physics and Superconductivity Department, Moscow State University , 119991 Moscow, Russia
A N Vasiliev: Low Temperature Physics and Superconductivity Department, Moscow State University , 119991 Moscow, Russia

DOI: https://doi.org/10.1088/1367-2630/14/10/103053
Journal volume & issue: Vol. 14, no. 10
p. 103053

Abstract

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The ultrafast quasiparticle dynamics of Fe _1+ _y Se _1− _x Te _x single crystals were investigated by dual-color transient reflectivity measurements (Δ R / 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 Δ R / R . Such a small λ demonstrates the unconventional origin of superconductivity in FeSe. Moreover, the temperature-dependent Δ R / 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.

Published in New Journal of Physics

ISSN: 1367-2630 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Science: Physics
Website: https://iopscience.iop.org/journal/1367-2630

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