Y-89 NMR-STUDY OF THE ANISOTROPY OF THE STATIC AND DYNAMIC SUSCEPTIBILITIES IN YBA2CU3O6+X

We report Y-89 NMR shift (K) and spin-lattice relaxation (T1) data on oriented YBa2Cu3O6+x powders, with x=1 and x=0.64. The anisotropy of K is shown to be dominated by that of the spin susceptibility on the oxygen sites chi(ab)(O)/chi(ab)(O)=1.2+/-0.05, which agrees with that expected on the Cu sites, and with a single-spin fluid picture for the CuO2 band. The anisotropy of T1 is compatible with a nearly isotropic spin lifetime in the q is similar to 0 dynamic susceptibility. Deviations from T1TK is similar to const are found at high T for both the underdoped (x=0.64) and the overdoped sample (x=1).