Our joint theoretical and computer experimental study of heat-to-spin conversion reveals that noncollinear antiferromagnetic insulators are promising materials for generating magnon spin currents upon application of a temperature gradient: They exhibit spin Seebeck and spin Nernst effects. Using Kubo theory and spin dynamics simulations, we explicitly evaluate these effects in a single kagome sheet of potassium iron jarosite, ${\mathrm{KFe}}_3{\left(\mathrm{OH}\right)}_6{\left({\mathrm{SO}}_4\right)}_2$, and predict a spin Seebeck conversion factor of $0.2\mu \mathrm{V}/\mathrm{K}$ at a temperature of $20\mathrm{K}$.

• Received 28 February 2019

DOI:https://doi.org/10.1103/PhysRevB.100.100401