# Intrinsic spin Nernst effect of magnons in a noncollinear antiferromagnet

## TL;DR

This paper develops a theoretical framework to analyze the intrinsic magnon spin current in noncollinear antiferromagnetic insulators, predicting a measurable spin Nernst effect influenced by symmetry considerations.

## Contribution

It introduces a new definition of magnon spin current in noncollinear antiferromagnets and formulates a linear response theory accounting for symmetry effects.

## Key findings

- Magnon spin current can be non-conserved but averages to zero under certain symmetries.
- The theory predicts a measurable spin Nernst response in specific materials.
- Symmetry considerations critically influence the magnon spin response.

## Abstract

We investigate the intrinsic magnon spin current in a noncollinear antiferromagnetic insulator. We introduce a definition of the magnon spin current in a noncollinear antiferromagnet and find that it is in general non-conserved, but for certain symmetries and spin polarizations the averaged effect of non-conserving terms can vanish. We formulate a general linear response theory for magnons in noncollinear antiferromagnets subject to a temperature gradient and analyze the effect of symmetries on the response tensor. We apply this theory to single-layer potassium iron jarosite KFe$_3$(OH)$_6$(SO$_4$)$_2$ and predict a measurable spin current response.