Aurélien Manchon
K. Sourounis, L. Saleem, D. Huang, Aurélien Manchon
Aix-Marseille Univ, CNRS, CINaM, Marseille, France
In insulating magnets, the anomalous transport of magnons is governed by the geometrical properties of the wave functions, in particular, their Berry curvature. To date, most theoretical studies of magnon transport have been conducted assuming non-interacting magnons. Because magnon interactions are ubiquitous in magnetic materials, sometimes even at zero temperature, the geometrical properties strongly depend on the temperature and are deeply influenced by interactions. To assess the impact of interactions on the transport properties of magnons, we investigated various situations in which such interactions are central. I will first discuss the impact of three- and four-magnon interactions in a collinear antiferromagnet, demonstrating that the former enhances the spin Nernst effect, whereas the latter quenches it, resulting in an overall spin Nernst conductivity that is about one order of magnitude smaller than that predicted by neglecting the interactions. I will also discuss how magnon interactions can drive topological phase transitions. As a matter of fact, in a magnetic Weyl semimetal, the electron-magnon interactions can induce a transition towards the magnetic insulating state, even below the Curie temperature. I will conclude by giving some perspectives.