Dynamics in the S=1 one-dimensional antiferromagnet AgVP2S6 via P-31 and V-51 NMR

The nuclear spin-lattice relaxation rate (1/T-1) has been measured at P-31 and V-51 nuclei in the one-dimensional spin-1 antiferromagnet AgVP2S6 single crystal. In addition to an activated temperature dependence, 1/T-1 at P sites shows 1/root H magnetic field dependence; due to spin diffusion above a certain cutoff field at high temperatures. While the diffusion constant shows a modest temperature dependence, the cutoff field increases rapidly on cooling. The spin-diffusion model is incompatible with the data at low temperatures, suggesting a crossover at T similar to 100 K.