Spin dynamics in the carrier-doped S=1/2 triangular lattice of NaxCoO2•yH2O -: art. no. 237201

We probed the local electronic properties of the mixed-valent Co+4-x triangular lattice in NaxCoO2 . yH(2)O by Co-59 NMR. We observed two distinct types of Co sites for x greater than or equal to 1/2, but the valence seems averaged out for x similar to 1/3. Local spin fluctuations exhibit qualitatively the same trend down to similar to 100 K regardless of the carrier concentration x, and hence the nature of the electronic ground state. A canonical Fermi-liquid behavior emerges below similar to 100 K only for x similar to 1/3.