Phonon softening in Nax Co O2·y H2 O: Implications for the Fermi surface topology and the superconducting state

J. P. Rueff, M. Calandra, M. D'Astuto, Ph Leininger, A. Shukla, A. Bosak, M. Krisch, H. Ishii, Y. Cai, P. Badica, T. Sasaki, K. Yamada, K. Togano

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

In this work we investigate the relevance of phonons for the superconductivity in Na0.35 Co O2·1.3 H2 O. We measure phonon dispersion in this material as well as in the nonhydrated parent compound Na0.7 Co O2 by inelastic x-ray scattering. The measured phonon dispersion along the Γ-M direction shows a marked softening of Co-related optical phonon branches close to the Brillouin zone boundary, with hole doping. The phonon spectra, dispersion, and softening of Co-vibration modes are well reproduced by first-principles calculations. The critical temperature estimated from a phonon-mediated mechanism is much lower than the measured one, suggesting a nonconventional superconducting state in this material.

Original languageEnglish
Article number020504
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume74
Issue number2
DOIs
Publication statusPublished - 2006 Jul 24

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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