SPIN SUSCEPTIBILITY AND DOPING DEPENDENCE IN TL0.5PB0.5SR2CA1-XYXCU2O7-DELTA AROUND THE METAL-INSULATOR-TRANSITION CU-63, CU-65, PB-207 ANDTL-205 NMR AND SPIN-LATTICE RELAXATION

NMR line shifts of Cu-63, Pb-207 and Tl-205 were measured in the cupra tes Tl0.5Pb0.5Sr2Ca1-xYxCu2O7 (x=0.0-1.0) in order to investigate the evolution of the spin susceptibility chi(S) around the metal-insulator transition, which occurs when the yttrium content increases up to x c ongruent-to 0.6. The Knight shift was evaluated for Pb-207 and Tl-205 and the corresponding change of the static spin susceptibility chi(S)( q=0) was determined from the NMR data in the normal and in the superco nducting state. In the superconducting phase, where T(c) has a maximum at x=0.2, the value of chi(S)(q=0) increases gradually with hole dopi ng. The Cu-63 zero-field NMR and the NMR spectra of Pb-207 and Tl-205 for Tl0.5Pb0.5Sr2YCu2O7 reported here present the first NMR observatio n of antiferromagnetic ordering in these thallium-based cuprates.