Magnetic heat conductivity in $\rm\bf CaCu_2O_3$: linear temperature dependence

TL;DR

This study measures the thermal conductivity of CaCu2O3, revealing a dominant magnetic contribution that is linearly dependent on temperature, consistent with theoretical models of a 1D Heisenberg chain.

Contribution

It provides experimental evidence of magnetic heat transport in CaCu2O3 with a linear temperature dependence, aligning with theoretical predictions for a S=1/2 Heisenberg chain.

Findings

Magnetic thermal conductivity is dominant along the chain direction.

The magnetic contribution to thermal conductivity is linear in temperature.

The magnetic mean free path is approximately 22 Å.

Abstract

We present experimental results for the thermal conductivity $\kappa$ of the pseudo 2-leg ladder material $\rm CaCu_2O_3$. The strong buckling of the ladder rungs renders this material a good approximation to a $S=1/2$ Heisenberg-chain. Despite a strong suppression of the thermal conductivity of this material in all crystal directions due to inherent disorder, we find a dominant magnetic contribution $\kappa_\mathrm{mag}$ along the chain direction. $\kappa_\mathrm{mag}$ is \textit{linear} in temperature, resembling the low-temperature limit of the thermal Drude weight $D_\mathrm{th}$ of the $S=1/2$ Heisenberg chain. The comparison of $\kappa_\mathrm{mag}$ and $D_\mathrm{th}$ yields a magnetic mean free path of $l_\mathrm{mag}\approx 22 \pm 5$ \AA, in good agreement with magnetic measurements.