Temperature-induced magnonic Chern insulator in collinear antiferromagnets

Abstract

Thermal fluctuation in magnets causes temperature-dependent self-energy corrections in magnons; however, its effects on the topological orders of magnons is not well explored. Here we demonstrate that such corrections can induce a Chern insulating phase in two-dimensional collinear antiferromagnets with sublattice asymmetries by increasing temperature. We present the phase diagram of the system and show that the trivial magnon bands at zero temperature exhibit Chern insulating phase above a critical temperature before the paramagnetic phase transition. The self-energy corrections close and reopen the band gap at $\mathrm{\ensuremath{\Gamma}}$ or $\mathbf{K}$ points, accompanied by a magnon chirality switch and nontrivial Berry curvature transition. The thermal Hall effect of magnons or detecting the magnon polarization can highlight the experimentally prominent signatures of the topological transitions. We include the numerical results based on the van der Waals magnet ${\mathrm{MnPS}}_{3}$, calling for experimental implementation. Our work presents a paradigm for constructing topological phases that is beyond the linear spin wave theory.