CL-35 NMR-STUDY OF SPIN DYNAMICS IN SR2CUO2CL2

Measurements of the Cl-35 nuclear-spin-lattice relaxation rate (NSLR) are reported for Sr2CuO2Cl2 around the antiferromagnetic transition temperature T(N) = 260 +/- 0.5 K. The temperature dependence of the Cu2+ spin correlation length xi(T) is obtained indirectly by using the conventional description of NSLR and scaling arguments and compared with the xi(T) obtained in La2CuO4 by neutron scattering. In both systems xi(T) follows the two-dimensional Heisenberg behavior renormalized by quantum fluctuations except close to T(N) where a crossover to a power-law T dependence is observed in Sr2CuO2Cl2.