Topological Hall Response from Canted Antiferromagnetic Order in d-Electron Kagome Systems

In a two-dimensional kagome monolayer, a nontrivial intrinsic Berry curvature may arise in the d-electron system from the interaction with a non-collinear spin order induced by an underlying antiferromagnetic exchange. This opens the route for a quantum anomalous Hall effect in the multi-orbital system, even without an external magnetic field, explicit spin-orbit coupling or relativistic effects. For spin orders with an out-of-plane component, the scalar spin chirality is finite, and the integration of the Berry curvature over the Brillouin zone may yield integer Hall conductivities in units of e 2 /h. For a Fermi level within a nontrivial gap, the canted configuration offers, at least in principle, the posibility for a maximal Chern number, C = ±5. Candidate materials are considered in this paper. In existing materials, the electron hopping is generally highly anisotropic, leading to a quantum anomalous Hall effect with smaller Chern numbers. A topological phase transition between Hall plateaus of opposite C can be driven by flipping the out-of-plane component of the spin order, alluding to the potential of this system to applications in quantum information.