Diffusive energy transport in the S=1 Haldane chain compound AgVP2S6

TL;DR

This study investigates thermal conductivity in the S=1 chain compound AgVP2S6, revealing a magnon contribution to heat transport and its relation to spin diffusion, highlighting energy diffusion in one-dimensional spin systems.

Contribution

It provides the first detailed analysis of magnon-mediated thermal transport and its connection to spin diffusion in a S=1 Haldane chain compound.

Findings

Magnon contribution to thermal conductivity identified along chains.

Energy diffusion constant D_E(T) correlates with spin diffusion D_S(T).

Transport behavior aligns with diffusion caused by interactions in 1D S=1 spin systems.

Abstract

We present the results of measurements of the thermal conductivity $\kappa$ of the spin S=1 chain compound AgVP_2S_6 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 behaviour of both transport parameters is consistent with a diffusion process that is caused by interactions inherent to one-dimensional S=1 spin systems.