Thermal conductivity of R2CuO4, with R = La, Pr and Gd

TL;DR

This study measures the anisotropic thermal conductivity of R2CuO4 (R=La, Pr, Gd) single crystals, revealing magnetic excitations significantly contribute to heat transport within CuO2 planes, with variations linked to oxygen stoichiometry.

Contribution

It provides new measurements of thermal conductivity in Pr2CuO4 and Gd2CuO4, highlighting the impact of oxygen content on magnetic heat transport, which was less understood before.

Findings

Magnetic excitations contribute to in-plane thermal conductivity.

Differences in magnetic thermal conductivity linked to oxygen stoichiometry.

Lower kappa_mag values in Pr2CuO4 and Gd2CuO4 compared to La2CuO4.

Abstract

We present measurements of the in-plane kappa_ab and out-of-plane kappa_c thermal conductivity of Pr2CuO4 and Gd2CuO4 single crystals. The anisotropy gives strong evidence for a large contribution of magnetic excitations to kappa_ab i.e. for a heat current within the CuO2 planes. However, the absolute values of kappa_mag are lower than previous results on La2CuO4. These differences probably arise from deviations from the nominal oxygen stoichiometry. This has a drastic influence on kappa_mag, which is shown by an investigation of a La2CuO4+delta polycrystal.