Topological magnons emerge as topologically protected spin wave states at the edges of magnets. In our recent work published in Physical Review B, 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.
Figure: A heterostructure composed of a kagome AFM interfaced with an NM. Topological magnons, localized at the edge of the AFM, strongly couple to the charge carriers of the NM, resulting in an enhancement of the thermally driven spin current pumped into the NM. The green arrows represent the DMI vectors along the various bonds.