Ultrafast transient response and electron-phonon coupling in the iron-pnictide superconductor Ba(Fe1−xCox)2As2 - École polytechnique Access content directly
Journal Articles Physical Review B: Condensed Matter and Materials Physics (1998-2015) Year : 2010

Ultrafast transient response and electron-phonon coupling in the iron-pnictide superconductor Ba(Fe1−xCox)2As2

Abstract

The transient response of Ba(Fe1−xCox)2As2, x=0.08 was studied by pump-probe optical reflectivity. After ultrafast photoexcitation, hot electrons were found to relax with two different characteristic times, indicating the presence of two distinct decay channels: a faster one, of less than 1 ps in the considered pump fluence range and a slower one, corresponding to lattice thermalization and lasting ≅6 ps. Our analysis indicates that the fast relaxation should be attributed to preferential scattering of the electrons with only a subset of the lattice-vibration modes with a second moment of the Eliashberg function λ⟨ω^2⟩≅64 meV^2. The simultaneous excitation of a strong fully symmetric A1g optical phonon corroborates this conclusion and makes it possible to deduce the value of λ≅0.12. This small value for the electron-phonon coupling confirms that a phonon-mediated process cannot be the only mechanism leading to the formation of superconducting pairs in this family of pnictides.

Dates and versions

hal-00572659 , version 1 (02-03-2011)

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Barbara Mansart, Davide Boschetto, A. Savoia, F. Rullier-Albenque, F. Bouquet, et al.. Ultrafast transient response and electron-phonon coupling in the iron-pnictide superconductor Ba(Fe1−xCox)2As2. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2010, 82 (2), pp.024513. ⟨10.1103/PhysRevB.82.024513⟩. ⟨hal-00572659⟩
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