Large Chern-Number Quantum Anomalous Hall Effect from Canted Antiferromagnetic Order in $d$-Electron System on Kagome Lattice

Abstract: Electrons of $d$-symmetry in a kagome lattice are considered which interact with non-collinear antiferromagnetic order in the absence of spin-orbit coupling. The non-collinearity of spin texture gives rise to non-relativistic spin splitting and the associated intrinsic Berry curvature. The integral of the latter over the Brillouin zone becomes nontrivial for non-coplanar (canted) non-collinear spin order even without explicit on-site or transfer spin-orbit coupling. That gives rise to a nonzero (scalar) spin chirality, and a record value for the Chern number of $C=\pm 5$ can appear when the Fermi level is in an appropriate gap for isotropic electron hopping integrals, or nearly isotropic ones. The numerical results for this topological quantum anomalous Hall effect are supported by an analytical formula. It is possible to split the $C=\pm 5$ plateau into different possible nonzero values for the Chern number by varying the onsite energies. The topological phase transitions between Hall plateaus can be driven by flipping the Zeeman-like exchange field or controlling the onsite energies, alluding to the potential of this system to quantum information.