Spin singlet pairing in the superconducting state of Nax Co O2 •1.3 H2 O: Evidence from a Co59 Knight shift in a single crystal

Guo Qing Zheng, Kazuaki Matano, D. P. Chen, C. T. Lin

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63 Citations (Scopus)

Abstract

We report a Co59 Knight-shift measurement in a single crystal of the cobalt oxide superconductor Nax Co O2 •1.3 H2 O (Tc =4.25 K). We find that the shift due to the spin susceptibility, Ks, is substantially large and anisotropic, with the spin shift along the a -axis Kas being two times that along the c -axis Kcs. The shift decreases with decreasing temperature (T) down to T≈100 K, then becomes a constant until superconductivity sets in. Both Kas and Kcs decrease below Tc. Our results indicate unambiguously that the electron pairing in the superconducting state is in the spin singlet form.

Original languageEnglish
Article number180503
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume73
Issue number18
DOIs
Publication statusPublished - May 15 2006

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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