Evidence of one-dimensional magnetic heat transport in the triangular-lattice antiferromagnet Cs$_2$CuCl$_4$

TL;DR

This study investigates low-temperature heat transport in the triangular-lattice antiferromagnet Cs$_2$CuCl$_4$, revealing anisotropic magnetic excitations contributing to heat conduction, especially along the direction of strongest exchange interaction.

Contribution

It provides experimental evidence of one-dimensional magnetic heat transport in Cs$_2$CuCl$_4$, highlighting anisotropic magnetic excitations' role in thermal conductivity.

Findings

Broad maxima in thermal conductivity at ~5 K explained by phonon scattering.

Field-dependent anomaly observed along the b axis near magnetic transition.

Anisotropic heat transport linked to magnetic excitations along the exchange interaction direction.

Abstract

We report on low-temperature heat-transport properties of the spin-1/2 triangular-lattice antiferromagnet Cs$_2$CuCl$_4$. Broad maxima in the thermal conductivity along the three principal axes, observed at about 5 K, are interpreted in terms of the Debye model, including the phonon Umklapp scattering. For thermal transport along the $b$ axis, we observed a pronounced field-dependent anomaly, close to the transition into the three-dimensional long-range-ordered state. No such anomalies were found for the transport along the $a$ and $c$ directions. We argue that this anisotropic behavior is related to an additional heat-transport channel through magnetic excitations, that can best propagate along the direction of the largest exchange interaction. Besides, peculiarities of the heat transport of Cs$_2$CuCl$_4$ in magnetic fields up to the saturation field and above are discussed.