Topological magnon insulator with a Kekulé Bond Modulation

We examine the combined eects of a Kekule coupling texture (KC) and a Dzyaloshinskii{Moriya interaction (DMI) in a two{dimensional ferromagnetic honeycomb lattice. By analyzing the gap closing conditions and the inversions of the bulk bands, we identify the parameter range in which the system behaves as a trivial or a nontrivial topological magnon insulator. We nd four topological
phases in terms of the KC parameter and the DMI strength. We present the bulk-edge correspondence for the magnons in a honeycomb lattice with an armchair or a zigzag boundary. Furthermore, we nd Tamm-like edge states due to the intrinsic on-site interactions along the boundary sites. Our results may have signicant implications to magnon transport properties in the 2D magnets at low temperatures.