Transversal transport of magnons in a modified Lieb lattice

TL;DR

This paper investigates magnon transport in a modified Lieb lattice, revealing Hall-like effects driven by Berry curvature despite trivial band topology, and explores their dependence on various physical parameters.

Contribution

It introduces a two-band magnon model on a modified Lieb lattice with Dzyaloshinskii-Moriya interaction, analyzing topological effects and transport properties.

Findings

Finite Berry curvature induces Hall-like magnon transport.

Transport coefficients depend on temperature, exchange couplings, DMI, and magnetic field.

The system exhibits trivial band topology despite non-zero Berry curvature.

Abstract

We studied a two-band magnon insulating model whose geometry is that of a modified Lieb lattice in which one of the sites was removed. Anisotropic ferromagnetic exchange interactions exist between the three nearest neighbors, and the anisotropy opens a gap in the magnon energy band structure. A non-vanishing Berry curvature is induced by a Dzyaloshinskii-Moriya interaction (DMI). The topology of the bands is trivial (in the sense of a null Chern number), but the finite Berry curvature induces Hall-like transport effects whose coefficients were calculated. Their dependence on temperature was studied and shows a resemblance with other magnon insulating systems found in the literature. The dependence on exchange couplings, DMI parameter, and external magnetic field was also investigated.