Chiral domain coarsening in frustrated itinerant magnets

Itinerant magnets are characterized by an electron-mediated spin-spin interaction that is long-ranged and dependent on the underlying electron Fermi surface. This effective interaction is also often frustrated, giving rise to complex spin textures at low temperatures. In particular, the kondo lattice model with classical Heisenberg spins on the triangular lattice exhibits an unusual non-coplanar magnetic structure, known as the all-out order, with a quadrupled unit cell at both 1/4 and 3/4 electron filling fractions. Moreover, the all-out order breaks the chiral symmetry, and the corresponding electronic state is an effective quantum Hall insulator as electrons acquire a nontrivial Berry phase from the non-coplanar spins. Importantly, while the long-range magnetic ordering is destroyed by thermal fluctuations, the chirality can persist up to a finite temperature. Here we combine Landau-Lifshitz dynamics with efficient electronic structure method to investigate the coarsening of the chiral domains after a thermal quench. As the chiral order is characterized by a Z2 symmetry-breaking, the growth of the chiral domains is expected to follow that of a non-conserved Ising-like order. We compare our numerical results against the expected scaling behaviors and discuss how the differences can be attributed to the unusual domain-wall structures and dynamics.