Effect of zinc impurities on the thermal Hall conductivity of Cu₃TeO₆

Cu₃TeO₆ (CTO) is a cubic antiferromagnetic insulator whose large negative thermal Hall conductivity (κ_xy) has been attributed to phonons [1], on the basis, for example, that κ_xy(T) mirrors the phonon dominated thermal conductivity κ_xx(T), with both peaking at the same temperature.

However, as in the case of many other insulators, the mechanism by which phonons produce a thermal Hall effect remains unknown.

Here we aim to shed light on the underlying mechanism by studying the effect of adding Zn impurities to Cu₃TeO₆, substituting for Cu. We present κ_xy data for various levels of Zn impurities, up to 9%.

We find that these impurities have a strong effect on κ_xy(T).

We discuss these effects in terms of various theoretical scenarios based on impurity or defect scattering of phonons [2,3,4].

[1] Chen et al., PNAS 119, e2208016119 (2022).

[2] Flebus and MacDonald, Phys. Rev. B 105, L220301 (2022).

[3] Sun et al., arXiv:2109.12117 (2021).

[4] Guo et al., arXiv:2201.11681 (2022).