Dynamics in the $\mathit{S}=1\mathrm{}$ One-Dimensional Antiferromagnet AgV${\mathrm{P}}_2$${\mathrm{S}}_6$ via ${}^{31}$P and ${}^{51}$V NMR

The nuclear spin-lattice relaxation rate $\left({1/T}_1\right)$ has been measured at ${}^{31}$P and ${}^{51}$V nuclei in the one-dimensional spin-1 antiferromagnet AgV${\mathrm{P}}_2$${\mathrm{S}}_6$ single crystal. In addition to an activated temperature dependence, ${1/T}_1$ at P sites shows $1/\sqrt{H}$ 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 $T\sim 100$ K.