  We study gauge fields produced by gradients of the Dzyaloshinskii-Moriya
interaction and propose a model of AFM topological insulator of magnons. In the
long wavelength limit, the Landau levels induced by the inhomogeneous
Dzyaloshinskii-Moriya interaction exhibit relativistic physics described by the
Klein-Gordon equation. The spin Nernst response due to the formation of
magnonic Landau levels is compared to similar topological responses in skyrmion
and vortex-antivortex crystal phases of AFM insulators. Our studies show that
AFM insulators exhibit rich physics associated with topological magnon
excitations.
