| Abstract: | We study the topological properties of magnon excitations in a wide class of three-dimensional(3 D) honeycomb lattices with ferromagnetic ground states. It is found that they host nodal ring magnon excitations. These rings locate on the same plane in the momentum space. The nodal ring degeneracy can be lifted by the DzyaloshinskiiMoriya interactions to form two Weyl points with opposite charges. We explicitly discuss these physics in the simplest 3 D honeycomb lattice and the hyerhoneycomb lattice, and show drumhead and arc surface states in the nodal ring and Weyl phases, respectively, due to the bulk-boundary correspondence. |
