Amplifying the antiferromagnetic spin Seebeck effect through topological magnons

TL;DR

This paper theoretically demonstrates that topological magnons at the edges of antiferromagnets can significantly amplify the spin Seebeck effect, especially when influenced by Dzyaloshinskii-Moriya interaction, leading to potential spintronic applications.

Contribution

It introduces a microscopic model showing how topological magnons enhance the spin Seebeck effect in antiferromagnet/metal heterostructures, highlighting the role of DMI and broken mirror symmetry.

Findings

Topological magnons contribute 4-5 times more to SSE than trivial magnons.

The SSE enhancement is highly sensitive to DMI strength.

Surface states of topological magnons are strongly coupled to charge carriers.

Abstract

Topological magnons emerge as topologically protected spin wave states at the edges of magnets. Here, we theoretically explore how these surface states can be harnessed to amplify the spin Seebeck effect (SSE) in antiferromagnets (AFMs) interfaced with normal metals (NMs). Based on a microscopic model of a kagome AFM, we demonstrate that broken mirror symmetry, combined with the Dzyaloshinskii-Moriya interaction (DMI), drives the system into a topological phase hosting spin-polarized magnons at the boundaries. Notably, linear response calculations reveal that in AFM/NM heterostructures, the topological magnons exhibit strong coupling to the metal's charge carriers, resulting in a substantial enhancement of the SSE. The relative contribution of the topological magnons is found to be 4-5 times greater than that of the trivial magnon bands. Moreover, our results show that this enhancement is highly sensitive to the strength of the DMI.