The transport of magnons in materials with topological non-trivial ground state has been investigated in various platforms (ferro- and antiferromagnets) and is characterized by anomalous mechanisms such as the thermal Hall effect and the magnon Nernst effect. Usually, these investigations are done in the framework of the Linear Spin Wave Theory and the interactions between magnons are ignored. In fact, due to the bosonic nature of magnons, such interactions can have a dramatic impact on the magnon lifetime Chernyshev, AL et al., Phys. Rev. Lett. 117, 187203 (2016) and band structure Mook et al., Phys. Rev. X 11, 021061 (2021), as recently demonstrated. In other words, these interactions are ubiquitous and can cause the alteration of the energy bands and the transport properties of the system, including damping and topological phase transitions Y.S. Lu et al., Phys. Rev. Lett. 127, 217202 (2021). In this work, we investigate the influence of magnon-magnon interactions on the anomalous transport of magnons in a topologically non-trivial honeycomb antiferromagnet. Focusing on the magnon spin Nernst effect, we uncover the impact of these interactions on the magnon lifetime, band structure and anomalous transport upon increasing the temperature.

References
Chernyshev, AL et al., Phys. Rev. Lett. 117, 187203 (2016) Mook et al., Phys. Rev. X 11, 021061 (2021) Y.S. Lu et al., Phys. Rev. Lett. 127, 217202 (2021)