In spite of flourishing studies on the topology of spin waves, a generic framework to classify and compute magnon band topology in non-collinear magnets is still missing. In this work we provide such a theory framework, by mapping an arbitrary linear spin wave into a local free-fermion Hamiltonian with exactly the same spectrum, symmetry implementation and band topology, which allows for a full classification and calculation on any topological properties of magnon bands. We apply this fermionization approach to honeycomb Kitaev magnet α-RuCl3, and show the existence of topologically protected magnon band crossings, and field-induced magnon Chern bands under small magnetic fields.
@article{arxiv.1807.05232,
title = {Magnon band topology in spin-orbital coupled magnets: classification and application to $\alpha$-RuCl$_3$},
author = {Fuyan Lu and Yuan-Ming Lu},
journal= {arXiv preprint arXiv:1807.05232},
year = {2018}
}