Intrinsic Magnon Nernst Effects in Pyrochlore Iridate Thin Films

TL;DR

This paper theoretically investigates the magnon Nernst effect in pyrochlore iridate thin films, revealing topologically protected edge modes and potential for spin caloritronic applications.

Contribution

It introduces a strong coupling approach to analyze magnon spin transport in [111] pyrochlore iridate thin films, highlighting the role of Dzyaloshinskii-Moriya interaction and topological magnon bands.

Findings

Identification of topologically protected chiral edge modes.

Temperature-dependent magnon Nernst response calculated.

Potential application in thermal spin transport devices.

Abstract

We theoretically study the magnon spin thermal transport using a strong coupling approach in pyrochlore iridate trilayer thin films grown along the [111] direction. As a result of the Dzyaloshinskii-Moriya interaction (DMI), the spin configuration of the ground state is an all-in/all-out ordering on neighboring tetrahedra of the pyrochlore lattice. In such a state, the system has an inversion symmetry and a Nernst-type thermal spin current response is well defined. We calculate the temperature dependence of the magnon Nernst response with respect to the magnon band topology controlled by the spin-orbit coupling parameters and observe topologically protected chiral edge modes over a range of parameters. Our study complements prior work on the magnon thermal Hall effect in thin-film pyrochlore iridates and suggests that the [111] grown thin-film pyrochlore iridates are a promising candidate for thermal spin transport and spin caloritronic devices.