SPIN-LATTICE RELAXATION OF CU-63 IN HIGH-T(C) RELATED ANTIFERROMAGNETIC CU OXIDES

We have made the measurements of the temperature dependence of the nuclear spin-lattice relaxation rate 1/T1 of Cu-63 in La2CuO4, YBa2Cu3O6 and CuO. At 4.2 K, 1/T1 of La2CuO4, YBa2Cu3O6 and CuO are about 5 x 10(4) sec-1, 5 x 10(3) sec-1 and 3 x 10(-3) sec-1 respectively. The sharp temperature dependence of 1/T1 has been observed in CuO, while in La2CuO4 1/T1 has exhibited a T2- 3 dependence below 4.2 K and has become nearly temperature independent above 4.2 K. In YBa2Cu3O6 1/T1 has exhibited a weak temperature dependence with nearly T2/3 dependence. The observed behaviors in CuO are in general accord with the theoretical prediction based on the spin wave picture if we take its low dimensional nature into account while those in other two compounds are not consistent with the theoretical prediction.