NMR and NQR studies of the pairing symmetry in the superconducting state of NaxCoO2 center dot 1.3H(2)O

K. Matano
G.-Q. Zheng
D. P. Chen
C. T. Lin
J. Cmaidalka
R. L. Meng
W. Chu

We report intensive studies on the cobalt oxide superconductors NaxCoO2 center dot 1.3H(2)O via Co-59 NMR and NQR measurements. In the sample with x = 0.26 and T-c = 4.6, we find that the spin-lattice relaxation rate 1/T-1 shows a T-3 variation below T-c and down to very low temperatures, which indicates the presence of line nodes in the superconducting (SC) gap function. We have also studied the spin susceptibility below T-c via the Knight shift measurement. The spin part of the Knight shift decreases below T-c in both the a- and c-directions indicating singlet spin state of the Cooper pairs. Our results strongly suggest that the superconducting state is a d-wave state. (c) 2006 Elsevier B. V. All rights reserved.

Journal of Magnetism and Magnetic Materials

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10.1016/j.jmmm.2006.10.531

https://doi.org/10.1016/j.jmmm.2006.10.531
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