Magnonic Su-Schriffer-Heeger Model in Honeycomb Ferromagnets

We study a collinear honeycomb ferromagnet with variable nearest-neighbor exchange interactions in the presence of the next nearest-neighbor Dzyaloshinskii-Moriya interaction. By examining the band topology and the associated chiral edge states, we find that varying the nearest-neighbor exchange interactions can induce topological phase transitions between trivial insulators with vanishing Chern number C=0 and magnon Hall insulators with C=1. Such a phase transition from topological trivial phase into a topological nontrivial one can be characterized by a sharp increase of the thermal Hall conductivity, which is attributed to the emerge of the topologically protected chiral edge states of magnons. Moreover, the magnon Hall state is robust against magnon-photon interactions. Possible materials realization is also discussed.