Cu63 nuclear transverse relaxation rate and spin correlations in YBa2Cu3O6.63

The Cu63 nuclear transverse relaxation rate in the normal state of YBa2Cu3O6.33 (Tc=62 K) is reported here. The Gaussian relaxation rate 1/T2G at the planar Cu sites increases with decreasing temperature from 300 down to 100 K, below which it becomes independent of temperature. This behavior is quite different from the nuclear spin-lattice relaxation rate 1/(T1T), which shows a peak near 150 K, and indicates that antiferromagnetic spin correlations in the CuO2 planes continue to grow in the temperature range where the low-frequency spin fluctuations are depressed by a spin gap. © 1994 The American Physical Society.