Magnon Heat Transport in doped $\rm La_2CuO_4$

TL;DR

This study investigates magnon-mediated heat transport in doped La2CuO4, revealing anisotropic thermal conductivity and how non-magnetic Zn doping suppresses magnon heat conduction, with a semiclassical model explaining the results.

Contribution

It provides experimental data on magnon heat transport in doped La2CuO4 and introduces a model linking magnon mean free path to Zn doping concentration.

Findings

Magnon thermal conductivity is highly anisotropic.

Zn doping suppresses magnon heat conduction.

Magnon mean free path scales linearly with inverse Zn concentration.

Abstract

We present results of the thermal conductivity of $\rm La_2CuO_4$ and $\rm La_{1.8}Eu_{0.2}CuO_4$ single-crystals which represent model systems for the two-dimensional spin-1/2 Heisenberg antiferromagnet on a square lattice. We find large anisotropies of the thermal conductivity, which are explained in terms of two-dimensional heat conduction by magnons within the CuO$_2$ planes. Non-magnetic Zn substituted for Cu gradually suppresses this magnon thermal conductivity $\kappa_{\mathrm{mag}}$. A semiclassical analysis of $\kappa_{\mathrm{mag}}$ is shown to yield a magnon mean free path which scales linearly with the reciprocal concentration of Zn-ions.