Honeycomb-lattice antiferromagnets have attracted wide attention for exploration of exotic heat transport and their interplay with magnetic excitations. In this work, we have revealed a contrasting behavior in the magneto-thermal conductivity (MTC) between two Co-based honeycomb-lattice magnets Co4M2O9 (M = Nb, Ta), despite their identical lattice structures and quite similar magnetism. Co4Ta2O9 exhibits enhanced MTC of about 550% at 9 T of an in-plane magnetic field, comparable to other honeycomb-magnets, while MTC for Co4Nb2O9 reaches only ~30%. This marked difference is ascribed to distinct features in the field-induced evolution of magnetic excitations that resonantly scatter phonons. This finding sheds light on implicit impacts of non-magnetic ions on thermal transport, and hints at the potential for broad heat-transport tunability while preserving magnetism and lattice structures.
@article{arxiv.2407.00963,
title = {Contrasting magnetothermal conductivity in sibling Co-based honeycomb-lattice antiferromagnets},
author = {Masato Ueno and Takashi Kurumaji and Shunsuke Kitou and Masaki Gen and Yuiga Nakamura and Yusuke Tokunaga and Taka-hisa Arima},
journal= {arXiv preprint arXiv:2407.00963},
year = {2024}
}