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

C. Hess·H. ElHaes·A. Waske·B. Büchner·C. Sekar·G. Krabbes·F. Heidrich-Meisner·W. Brenig
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Abstract

We present experimental results for the thermal conductivity $κ$ 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 $κ_\mathrm{mag}$ along the chain direction. $κ_\mathrm{mag}$ 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 $κ_\mathrm{mag}$ and $D_\mathrm{th}$ yields a magnetic mean free path of $l_\mathrm{mag}\approx 22 \pm 5$ Å, in good agreement with magnetic measurements.

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C. Hess, H. ElHaes, A. Waske, B. Büchner, C. Sekar, G. Krabbes, F. Heidrich-Meisner, W. Brenig. 2006-12-12. Magnetic heat conductivity in $\rm\bf CaCu_2O_3$: linear temperature dependence. https://doi.org/10.1103/physrevlett.98.027201

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