Chromium trihalides offer a rich playground for two-dimensional magnetism. In this talk, I will focus on one controversial member of this material class, CrI3, which can host topological magnons. By applying an external magnetic field, the magnetization direction and thus magnon dispersion relation and topological properties can be tuned. We compare the effect of this tuning in the two prominent models that have been suggested to describe CrI3, namely a Kitaev - vs. a Dzyaloshinskii–Moriya model, analytically and computationally. By observing the magnon dispersion relations [1] and a spin accumulation arising from the magnon Nernst effect [2], which carries signatures of the magnon topology, we point out different experimentally accessible observables to discriminate between the two models. Our setup is a versatile computational method to probe magnon topology in arbitrary magnetic insulators.
[1] Phys. Rev. B 109, 174425 (2024).
[2] arXiv:2409.15964.