Iron-specific phonon density of states in the superconductors LaFeAsO 1-xFx and La1-xCaxFePO

Satoshi Higashitaniguchi, Makoto Seto, Shinji Kitao, Yasuhiro Kobayashi, Makina Saito, Ryo Masuda, Takaya Mitsui, Yoshitaka Yoda, Yoichi Kamihara, Masahiro Hirano, Hideo Hosono

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Abstract

We measured element-specific Fe-phonon densities of states (Fe-PDOSs) of LaFeAsO1-x Fx (x=0,0.11) and La1-x Cax FePO (x=0.13) by nuclear resonant inelastic scattering of synchrotron radiation. Since the bands crossing the Fermi edge are mainly Fe3d bands, Fe is the key element for iron pnictide superconductivity, and therefore element-specific Fe-PDOS offers crucial information on the phonon contribution in iron pnictide superconductors. The measured Fe-PDOSs of superconductor LaFeAsO0.89 F0.11 (Tc =26 K) and that of nonsuperconductor LaFeAsO have similar structures both below Tc (15 K) and above Tc (298 K); therefore, fluorine doping does not have a notable effect on the Fe-PDOS. The measured Fe-PDOS of LaFeAsO1-x Fx agrees well with Fe-PDOS spectrum determined from a previous first-principles calculation and shows structural resemblance with a calculated Iliashberg function α2 F (ω), which indicates small electron-phonon coupling. Therefore, our results indicate that phonons are not the main contributors to the high- Tc superconductivity of LaFeAsO1-x Fx.

Original languageEnglish
Article number174507
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume78
Issue number17
DOIs
Publication statusPublished - 2008 Nov 7

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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    Higashitaniguchi, S., Seto, M., Kitao, S., Kobayashi, Y., Saito, M., Masuda, R., Mitsui, T., Yoda, Y., Kamihara, Y., Hirano, M., & Hosono, H. (2008). Iron-specific phonon density of states in the superconductors LaFeAsO 1-xFx and La1-xCaxFePO. Physical Review B - Condensed Matter and Materials Physics, 78(17), [174507]. https://doi.org/10.1103/PhysRevB.78.174507