2004/02/03 by I. R. Mukhamedchine, H. Alloul, Mukhamedchine, I. R. +5
Physics and Astronomy · #FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el) #cond-mat.str-el
paper · pdf · doi:10.48550/arxiv.cond-mat/0402074
5 pages, 4 figures
arxiv created 2004/02/03 · arxiv updated 2009/12/01
We have compared by 23Na NMR and magnetic susceptibility the magnetic properties of oriented powder samples of NaxCoO2 compounds. The NMR spectra are found identical for various samples with nominal 0.50≤ x≤ 0.70, which establishes that the dominant phase has a single composition x≈ 0.70. Three Na sites are identified from their single valued quadrupole effects and magnetic shifts which implies a very definite order of the Na+ ions and of the Co charges in the CoO2 planes. The local susceptibility of the magnetic cobalt sites displays a large enhancement below 100 K with respect to the usually found high T Curie-Weiss law. A very distinct much weaker Pauli like magnetism is detected for x≈ 0.35, the parent of the superconducting hydrated compound.