  Topologically protected magnon surface states are highly desirable as an
ideal platform to engineer low-dissipation spintronics devices. However,
theoretical prediction of topological magnons in strongly correlated materials
proves to be challenging because the ab initio density functional theory
calculations fail to reliably predict magnetic interactions in correlated
materials. Here, we present a symmetry-based approach, which predicts
topological magnons in magnetically ordered crystals, upon applying external
perturbations such as magnetic/electric fields and/or mechanical strains. We
apply this approach to carry out an efficient search for magnetic materials in
the Bilbao Crystallographic Server, where, among 198 compounds with an over
300-K transition temperature, we identify 12 magnetic insulators that support
room-temperature topological magnons. They feature Weyl magnons with surface
magnon arcs and magnon axion insulators with either chiral surface or hinge
magnon modes, offering a route to realize energy-efficient devices based on
protected surface magnons.
