Comment on “Thermal properties of magnons in yttrium iron garnet at elevated magnetic fields”

Abstract

Rezende and L\'opez Ortiz [Phys. Rev. B 91, 104416 (2015)] published a calculation for the magnon specific heat and thermal conductivity of yttrium iron garnet in the presence of large magnetic fields. The results reproduced our previous temperature-dependent measurements of both quantities in fields up to 70 kOe [Phys. Rev. B 90, 064421 (2014)]. Here, we point out that the experimentally observed magnetic-field dependence of thermal conductivity shows a faster saturation than their model explains. Furthermore, their results do not affect the main conclusion of our paper regarding the magnon thermal mean-free path.