Topological magnons in the honeycomb-kagome lattice

Materials with magnon Hall effect have potential applications in the field of spintronics and magnonics. The experimental observations of the magnon Hall effect in three-dimensional pyrochlore ferromagnets and two-dimensional kagome ferromagnets inspired the search for topological magnons in various lattice structures. The honeycomb-kagome (HK) lattice (also known as the edge-centered honeycomb lattice) can be seen as the combination of the honeycomb and kagome lattices. Hence, the Dzyaloshinskii-Moriya (DM) interaction is allowed and topological magnons are expected in the HK lattice, as the cases in the honeycomb and the kagome lattices alone. Here, we study the topological magnons in the HK lattice by calculating its band structure, Chern number, edge states and thermal Hall conductivity. It is shown that there are rich topological phases and phase transitions with the tuning of the model parameters. The finite thermal Hall conductivity induced by the DM interaction also has interesting behaviors, which are related to the topological phase transitions.