Magnetic orderings from spin-orbit coupled electrons on kagome lattice

We investigate magnetic orderings on kagome lattice numerically from the tight-binding Hamiltonian of electrons, governed by the filling factor and spin-orbit coupling (SOC) of electrons. We find that even a simple kagome lattice model can host both ferromagnetic and noncollinear antiferromagnetic orderings depending on the electron filling, reflecting gap structures in the Dirac and flat bands characteristic to the kagome lattice. Kane--Mele- or Rashba-type SOC tends to stabilize noncollinear orderings, such as magnetic spirals and 120-degree antiferromagnetic orderings, due to the effective Dzyaloshinskii--Moriya interaction from SOC. The obtained phase structure helps qualitative understanding of magnetic orderings in various kagome-layered materials with Weyl or Dirac electrons.