Magnetic fluctuation and pairing instability controlled by the CoO6 distortion in the sodium cobalt oxide

Masahito Mochizuki; Youichi Yanase; Masao Ogata

doi:10.1016/j.physb.2006.01.486

Magnetic fluctuation and pairing instability controlled by the CoO₆ distortion in the sodium cobalt oxide

Masahito Mochizuki, Youichi Yanase, Masao Ogata

Research output: Contribution to journal › Article › peer-review

1 Citation (Scopus)

Abstract

We study how the CoO₆ distortion along the c-axis affects the magnetic properties and superconductivity in the novel Co-oxide superconductor Na_x CoO₂ · y H₂ O 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 language	English
Pages (from-to)	875-877
Number of pages	3
Journal	Physica B: Condensed Matter
Volume	378-380
Issue number	SPEC. ISS.
DOIs	https://doi.org/10.1016/j.physb.2006.01.486
Publication status	Published - 2006 May 1
Externally published	Yes

Keywords

CoO distortion
Hole-pocket Fermi surface
Multiorbital Hubbard model
Na CoO · y H O

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics
Electrical and Electronic Engineering

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title = "Magnetic fluctuation and pairing instability controlled by the CoO6 distortion in the sodium cobalt oxide",

abstract = "We study how the CoO6 distortion along the c-axis affects the magnetic properties and superconductivity in the novel Co-oxide superconductor Nax CoO2 · y H2 O 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 eg′ 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.",

keywords = "CoO distortion, Hole-pocket Fermi surface, Multiorbital Hubbard model, Na CoO · y H O",

author = "Masahito Mochizuki and Youichi Yanase and Masao Ogata",

note = "Funding Information: We thank K. Ishida, K. Yoshimura, K. Kobayashi, M. Sato, K. Kuroki, Y. Tanaka, H. Kontani, S. Onari, K. Yada for valuable discussions. This work is supported by “Grant-in-Aid for Scientific Research” from the MEXT of Japan.",

year = "2006",

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T1 - Magnetic fluctuation and pairing instability controlled by the CoO6 distortion in the sodium cobalt oxide

AU - Mochizuki, Masahito

AU - Yanase, Youichi

AU - Ogata, Masao

N1 - Funding Information: We thank K. Ishida, K. Yoshimura, K. Kobayashi, M. Sato, K. Kuroki, Y. Tanaka, H. Kontani, S. Onari, K. Yada for valuable discussions. This work is supported by “Grant-in-Aid for Scientific Research” from the MEXT of Japan.

PY - 2006/5/1

Y1 - 2006/5/1

N2 - We study how the CoO6 distortion along the c-axis affects the magnetic properties and superconductivity in the novel Co-oxide superconductor Nax CoO2 · y H2 O 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 eg′ 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.

AB - We study how the CoO6 distortion along the c-axis affects the magnetic properties and superconductivity in the novel Co-oxide superconductor Nax CoO2 · y H2 O 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 eg′ 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.

KW - CoO distortion

KW - Hole-pocket Fermi surface

KW - Multiorbital Hubbard model

KW - Na CoO · y H O

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