CU-63 AND O(17) NMR-STUDIES IN THE PLANE SITE IN YBA2CU3O7

The temperature dependence of the nuclear-spin-lattice relaxation rate . 1/T1 of both Cu and O sites in the CuO2 plane have been measured at high magnetic field of 11T. The ratio of (1/T1(Cu))/(1/T1(O))(R) above T(c) increases with decreasing temperature associated with the develo pment of antiferromagnetic (AF) spin correlation and stays constantly below 100K. while R is rapidly reduced Just below T(c). being differen t from the previous results. The decrease of R reflects intimately the reduction in the AF contribution to the spin-fluctuation spectral wei ght relative to the q approximately (0.0) part due to the gap opening.