NUCLEAR MAGNETIC-RELAXATION IN AN ISING-LIKE ANTIFERROMAGNET CSCOCL3 - DOMAIN-WALL DYNAMICS

The longitudinal relaxation time T-1 of Cs-133 NMR was measured in the low-temperature, intermediate, and paramagnetic phases of a quasi-one -dimensional S=1/2 Ising-like antiferromagnet CsCoCl3. The direction a nd the fluctuating rate of thr anisotropic local-held fluctuation at t he Cs site, which is caused by passage of domain walls in the Co2+ Lin ear chain, are determined by using a fluctuating-field analysis of NMR -line, frequency, and temperature dependences of 1/T-1. It is found th at the fluctuation in the low-temperature phase is of a biaxial pulsel ike type as a result of temporary spin inversion in the two chains on the triangular lattice, while that in the intermediate phase is of a u niaxial two-state type as a result of the spin inversion only in the d isordered chain. The fluctuating rate, ranged over eight orders of mag nitude, is obtained from the fluctuating-field analysis.