NMR AND NQR STUDIES OF SPIN CORRELATION AND SUPERCONDUCTIVITY IN HIGH-T(C) OXIDES

The magnetic and superconducting properties in high-T(c) cuprates have been investigated over a wide doping range by NMR and NQR of Cu-63 and O-17 in the lightly-doped La2-xSrxCuO4 (LSCO), YBa2Cu4O8 (Y124) and the heavily-doped Bi2Sr2CaCu2O8 (BSCO), Tl2Ba2CuO6+y (TBCO) and the Zn- and Ni-doped YBa2Cu3O7 (YBCO7). From extensive studies in the normal state, it is extracted that the uniform, chi(s)(T) and the staggered, chi(Q)(T) susceptibilities originating from the antiferromagnetic (AF) spin correlation are suppressed with increasing hole content and furthermore, the T-dependence of chi(s)(T) and chi(Q)(T) is changed from the T-increasing behavior with temperature and the Curie-Weiss one into the T-independent behavior, respectively. The superconducting properties cannot be accounted for by the conventional BCS model or other isotropic s-wave models. A d-wave model is applicable in interpreting consistently most of NMR results, if the finite density of states at the Fermi level is taken into consideration associated with the pair breaking effect. There are increasing evidences that the magnetic mechanism for the superconductivity is promising in high-T(c)