Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 59Co, 23Na, and 1H NMR Studies of Double-Layer Hydrated Superconductors
  NaxCoO2-yH2O   We present our NMR studies of double-layer hydrated cobalt oxides
NaxCoO2-yH2O (x ~ 0.35, y ~ 1.3) with various Tc = 0 - 4.8 K and magnetic
transition temperatures. High-resolution $^{1}$H NMR spectrum served as an
evidence for the existence of H$_{3}$O$^{+}$ oxonium ions. $^{23}$Na nuclear
spin-lattice relaxation rates served to detect local field fluctuations
sensitive to Tc. $^{59}$Co nuclear quadrupole resonance (NQR) spectra served to
classify the various Tc samples. From the classification by $^{59}$Co NQR
frequency, the double-layer hydrated compounds were found to have two
superconducting phases closely located to a magnetic phase. In the normal state
and at a magnetic field in the $ab$-plane, two $^{59}$Co NMR signals with
different Knight shifts and different $^{59}$Co nuclear spin-lattice relaxation
times $^{59}T_{1}$ were observed. The two $^{59}$Co NMR signals suggest
magnetic disproportionation of two Co sites or in-plane (XY) anisotropy of a
single Co site. Non Korringa behavior and power law behavior in zero-field NQR
1/$^{59}T_{1}$ above and below Tc suggest non-Fermi liquid and unconventional
superconductivity.

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The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: chao-dyn
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The categories of this paper are: alg-geom
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: hep-ph
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The categories of this paper are: physics
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th