Topological phase transition and thermal Hall effect in kagome ferromagnets

Abstract

We investigate a mechanism for phase transitions between topological magnon phases on the breathing kagome lattice ferromagnets with Dzyaloshinskii-Moriya interaction, which is induced by the lattice deformation. With the linear spin-wave theory, we calculate the magnonic Chern number, topological phase diagram, and magnon thermal Hall conductivity at low temperature with tunable modulated exchange interactions due to the lattice deformation. We show that the modulated exchange interactions and Dzyaloshinskii-Moriya interaction strength determine the band topology of magnons. We find a sign reversal of the thermal Hall conductivity during topological phase transitions explained in terms of topological edge modes and their propagation directions. We also discuss candidate materials to realize our ideas.