Pressure dependence of the superconducting transition and electron correlations in Nax Co O2·1.3 H2 O

E. Kusano, S. Kawasaki, K. Matano, Guo Qing Zheng, R. L. Meng, J. Cmaidalka, C. W. Chu

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6 Citations (Scopus)

Abstract

We report Tc and Co59 nuclear quadrupole resonance measurements on the cobalt oxide superconductor Nax Co O2·1.3 H2 O (Tc =4.8 K) under hydrostatic pressure (P) up to 2.36 GPa. Tc decreases with increasing pressure at an average rate of -0.49±0.09 K/GPa. At low pressures P≤0.49 GPa, the decrease of Tc is accompanied by a weakening of the spin correlations at a finite wave vector and a reduction of the density of states (DOS) at the Fermi level. At high pressures above 1.93 GPa, however, the decrease of Tc is mainly due to a reduction of the DOS. These results indicate that the electronic and magnetic state of Co is primarily responsible for the superconductivity. The spin-lattice relaxation rate 1/T1 at P=0.49 GPa shows a T3 variation below Tc down to T∼0.12 Tc, which provides compelling evidence for the presence of line nodes in the superconducting gap function.

Original languageEnglish
Article number100506
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume76
Issue number10
DOIs
Publication statusPublished - Sep 19 2007

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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