Spin dynamics studied by 89Y NMR in high Tc superconductor YBa2Cu3O6+x

89Y NMR shifts in the high Tc superconductor YBa2Cu3O6+x are compared with 17O NMR new data published by Yoshinari et al. and the orbital shift 89Korb is estimated to be 155 ppm. The nuclear spin lattice relaxation rate 89(1/T1T) for 89Y is found to be proportional to 17(1/T1T) for 17O at 2,3 plane sites, which supports the single spin fluid model. The relation T1TKS = const. is realized for 89Y nuclei in the oxygen depleted compounds YBa2Cu3O6+x. It is found that the relation T1TKS = const. means that the energy width of dynamical spin susceptibility χ''(q, ω) with the wave vector q ∼ 0, ℎΓ0, is independent of temperature although the uniform susceptibility χ0 strongly depends on temperature. It is also shown that the weight of the low q part of the spin excitation spectrum decreases with decreasing the hole concentration. (author)