Weak Magnetic Order in Bilayered-Hydrate Na_<i>x</i>CoO₂·<i>y</i>H₂O Structure Probed by Co Nuclear Quadrupole Resonance –Proposed Phase Diagram in Superconducting Na_<i>x</i>CoO₂·<i>y</i>H₂O–

• Ihara Yoshihiko

  Department of Physics, Graduate School of Science, Kyoto University

• Ishida Kenji

  Department of Physics, Graduate School of Science, Kyoto University

• Michioka Chishiro

  Department of Chemistry, Graduate School of Science, Kyoto University

• Kato Masaki

  Department of Chemistry, Graduate School of Science, Kyoto University

• Yoshimura Kazuyoshi

  Department of Chemistry, Graduate School of Science, Kyoto University

• Takada Kazunori

  Advanced Materials Laboratory, National Institute for Materials Science

• Sasaki Takayoshi

  Advanced Materials Laboratory, National Institute for Materials Science

• Sakurai Hiroya

  Superconducting Materials Center, National Institute for Materials Science

• Takayama-Muromachi Eiji

  Superconducting Materials Center, National Institute for Materials Science

書誌事項

タイトル別名

• Weak Magnetic Order in Bilayered-Hydrate NaxCoO2 yH2O Structure Probed by Co Nuclear Quadrupole Resonance-Proposed Phase Diagram in Superconducting NaxCoO2 yH2O-

抄録

A weak magnetic order was found in a nonsuperconducting bilayered-hydrate Na_xCoO₂·yH₂O sample by Co nuclear quadrupole resonance (NQR) measurement. The nuclear spin–lattice relaxation rate divided by temperature 1⁄T₁T shows a prominent peak at 5.5 K, below which a Co NQR peak splits due to an internal field at the Co site. From the analyses of the Co NQR spectrum at 1.5 K, the internal field is evaluated to be ∼300 Oe and found to be in the ab-plane. The magnitude of the internal field suggests that the ordered moment is as small as ∼0.015μ_B using the hyperfine coupling constant reported previously. It is shown that the NQR frequency ν_Q correlates with magnetic fluctuations from measurements of NQR spectra and 1⁄T₁T in various samples. The higher-ν_Q sample has stronger magnetic fluctuations. A possible phase diagram for Na_xCoO₂·yH₂O is depicted using T_c and ν_Q, in which the crystal distortion along the c-axis of the tilted CoO₂ octahedron is considered to be a physical parameter. Superconductivity with the highest T_c is seemingly observed in the vicinity of a magnetic phase, suggesting strongly that magnetic fluctuations play an important role in the occurrence of superconductivity.

収録刊行物

• Ｊｏｕｒｎａｌ　ｏｆ　ｔｈｅ　Ｐｈｙｓｉｃａｌ　Ｓｏｃｉｅｔｙ　ｏｆ　Ｊａｐａｎ

  Ｊｏｕｒｎａｌ　ｏｆ　ｔｈｅ　Ｐｈｙｓｉｃａｌ　Ｓｏｃｉｅｔｙ　ｏｆ　Ｊａｐａｎ 74 (3), 867-870, 2005

  一般社団法人 日本物理学会

キーワード

• superconductivity
• hydrate sodium cobalt oxide
• NQR
• spin fluctuations

詳細情報

• CRID: 1390001204186047360
• NII論文ID: 210000105902
• NII論文ID: 110001979459
• NII書誌ID: AA00704814
• DOI: 10.1143/jpsj.74.867
• BIBCODE: 2005JPSJ...74..867I
• ISSN: 13474073
• ISSN: 00319015
• NDL書誌ID: 7282558
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I7282558
• Web Site: https://journals.jps.jp/doi/pdf/10.1143/JPSJ.74.867
• 本文言語コード: en
• データソース種別:
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