Diffusive energy transport in the S=1 Haldane chain compound AgVP2S6 -: art. no. 094432

We present the results of measurements of the thermal conductivity kappa of the spin S=1 chain compound AgVP2S6 in the temperature range between 2 and 300 K and with the heat flow directed either along or perpendicular to the chain direction. The analysis of the anisotropy of the heat transport allowed for the identification of a small but non-negligible magnon contribution kappa(m) along the chains, superimposed on the dominant phonon contribution kappa(ph). At temperatures above about 100 K the energy diffusion constant D-E(T), calculated from the kappa(m)(T) data, exhibits similar features as the spin diffusion constant D-S(T), previously measured by NMR. In this regime, the behavior of both transport parameters is consistent with a diffusion process that is caused by interactions inherent to one-dimensional S=1 spin systems.