Degradation of superconductivity and spin fluctuations by electron over-doping in LaFeAsO$_{1-x}$F$_{x}$

S. Wakimoto; K. Kodama; M. Ishikado; M. Matsuda; R. Kajimoto; M. Arai; K. Kakurai; F. Esaka; A. Iyo; H. Kito; H. Eisaki; S. Shamoto

doi:10.1143/jpsj.79.074715

arXiv · 0906.2453

Degradation of superconductivity and spin fluctuations by electron over-doping in LaFeAsO$_{1-x}$F$_{x}$

S. Wakimoto·K. Kodama·M. Ishikado·M. Matsuda·R. Kajimoto·M. Arai·K. Kakurai·F. Esaka·A. Iyo·H. Kito·H. Eisaki·S. Shamoto

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Abstract

Low energy spin fluctuations are studied for the electron-doped Fe-based superconductor LaFeAsO(1-x)F(x) by inelastic neutron scattering up to the energy transfer of w = 15 meV using polycrystalline samples. Superconducting samples (x=0.057, Tc=25 K and x=0.082, Tc=29 K) show dynamical spin susceptibility chi"(w) almost comparable with the parent sample's. However chi"(w) is almost vanished in the x=0.158 sample where the superconductivity is highly suppressed. These results are compatible with the theoretical suggestions that the spin fluctuation plays an important role for the superconductivity.

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S. Wakimoto, K. Kodama, M. Ishikado, M. Matsuda, R. Kajimoto, M. Arai, K. Kakurai, F. Esaka, A. Iyo, H. Kito, H. Eisaki, S. Shamoto. 2010-05-06. Degradation of superconductivity and spin fluctuations by electron over-doping in LaFeAsO$_{1-x}$F$_{x}$. https://doi.org/10.1143/jpsj.79.074715

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