Ferromagnetic and triplet-pairing instabilities controlled by trigonal distortion of CoO6 octahedra in NaxCoO2· yH2O

Masahito Mochizuki, Youichi Yanase, Masao Ogata

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


In the recently discovered Co-oxide superconductor NaxCoO 2·yH2O, the edge-shared CoO6 octahedra are trigonally contracted along the c-axis in the CoO2-plane. We study how this CoO6 distortion affects the magnetic properties and superconductivity in this compound by analyzing the multiorbital Hubbard model using the fluctuation-exchange approximation. It is shown that through generating the trigonal crystal field, the distortion pushes the Co e′g bands up and consequently gives rise to the hole-pocket Fermi surfaces, which have been predicted in the band calculations. As the distortion increases, the hole pockets are enlarged and the ferromagnetic fluctuation as well as the pairing instability increases, which is in good agreement with recent NQR results.

Original languageEnglish
Pages (from-to)1670-1673
Number of pages4
Journaljournal of the physical society of japan
Issue number6
Publication statusPublished - 2005 Jun
Externally publishedYes


  • Co-oxide superconductor
  • Ferromagnetic fluctuation
  • Hole-pocket Fermi surfaces
  • Triplet pairing

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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