14 May 2026 Thu 11.30 am

Topological phases of matter are among the hottest topics in condensed matter physics. In particular, they can be realized in magnetic materials. The famous example is the skyrmion lattice observed in many compounds. Importantly, when coupled to itinerant electrons, it leads to peculiar transport properties. The giant topological Hall effect due to the emergent field, originating from topological charge of the skyrmions, was observed in frustrated antiferromagnets on high-symmetry lattices.

Recently another phase with intriguing properties was observed experimentally and discussed numerically. It is called a chiral stripe state and it is formed by a double-Q superposition of a helicoid and a transverse spin-density wave (SDW), realizing a superlattice of topological charge. Our analytical method, supported by Monte Carlo calculations, shows that the peculiar CS phase arises from an instability in the helimagnon dispersion of the conventional helical ground state. When the exchange interaction allows for several equivalent modulation vectors in high-symmetry lattices, exchange anisotropy destabilizes the excitation spectrum and induces the secondary SDW component. The analytical theory suggests that the CS state should be ubiquitous in triangular and square lattice materials, when spin-orbit coupling and dipolar interactions are taken into account. Finally, we discuss the effect of stripes of the emergent field  on the conduction electrons.

< Previous