Thermal Transport Properties of Magnons on the $\alpha$-T$_3$ Lattice

TL;DR

This paper explores the topological phases and thermal transport properties of magnons on the $lpha$-T$_3$ lattice, revealing multiple magnon insulator phases and their effects on thermal Hall conductivity.

Contribution

It identifies topologically trivial and non-trivial magnon insulator phases and analyzes their thermal Hall conductivities using atomistic spin dynamics simulations.

Findings

Identification of one trivial and three topological magnon insulator phases.

Magnon thermal Hall conductivity correlates with the Chern number of the lowest magnon band.

Sign of thermal Hall conductivity remains unchanged at phase boundaries.

Abstract

We theoretically investigate magnons on the $\alpha$-T$_3$ lattice. Atomistic spin dynamics simulations show that next-nearest neighbor hopping and easy-axis anisotropy stabilize ferromagnetic order in the presence of Dzyaloshinskii-Moriya interaction. We identify one topologically trivial magnon insulator phase and three magnon Chern insulator phases. The topologically trivial magnon insulator phase exhibits a small but non-zero magnon thermal Hall conductivity, while in the magnon Chern insulator phases the Chern number of the lowest magnon band dominates the magnon thermal Hall conductivity. The sign of the magnon thermal Hall conductivity does not change at the topological phase boundaries, but distinct changes are observed in the magnitude.