Chirality-driven Hall Transport Phenomena of Spins

TL;DR

This paper reviews the spin chirality origin of Hall transport phenomena in magnetic insulators, develops a formalism for thermal Hall response, and discusses recent experimental and theoretical advances including topological magnon effects and emergent gauge fields.

Contribution

It introduces a general linear response formalism for thermal Hall transport applicable to various spin regimes and explores topological magnon effects and emergent gauge fields in textured magnets.

Findings

Magnon-mediated thermal Hall transport observed in kagome and pyrochlore insulators.

Theoretical framework for spin chirality-driven Hall effects in different magnetic regimes.

Topological magnon Hall effect associated with Skyrmion textures.

Abstract

Experimental and theoretical aspects of Hall-type transport of spins in magnetic insulators are reviewed, with emphasis on their spin chirality origin. A general formalism for linear response theory of thermal Hall transport in the spin model is developed, which can be applied to both the magnon and the paramagnetic, spin-liquid regimes. Recent experiments on magnon-mediated thermal Hall transport in the two-dimensional kagome, and three-dimensional pyrochlore ferromagnetic insulators are reviewed in light of the multi-band magnon theory of Hall transport, and compared to the more mysterious thermal Hall transport found in the putative quantum spin ice material. As realizations of spin-chirality driven magnon transport in the real space, we review the general theory of emergent gauge fields governing the magnon dynamics in the textured magnet, and discuss its application to the magnon-Skyrmion scattering problem. Topological magnon Hall effect driven by the Skyrmion texture is discussed.