High bosonic Bott index and transport of multiband topological magnons
Phys. Rev. B 113, 064439 – Published 25 February, 2026
DOI: https://doi.org/10.1103/ny9t-sfmk
Abstract
Magnons are bosonic quasiparticles in magnetically ordered systems. Bosonic Bott index has been affirmed as a real-space topological invariant for a two-band ferromagnetic model. In this work, we theoretically investigate the topology and transport of magnons in a multiband bosonic kagome ferromagnetic model. We demonstrate the validity of the bosonic Bott indices of values larger than 1 in multiband magnonic systems by showing the agreement with Chern numbers in the clean limit and the bulk-boundary correspondence during the topological phase transition. For the high Bott index phase, the disorder-induced topological phase transition occurs in a multistep manner. Using a generalized Landauer-Büttiker formalism, we reveal how the magnon transport depends on Gilbert damping and disorder under coherent excitation or temperature difference. The results further justify the bosonic Bott index as a robust real-space topological invariant for multiband magnonic systems and provide insights into the transport of topological magnons.
