Optically controlled spin scalar chirality in centrosymmetric magnetic metals*

Noncoplanar and noncollinear spin textures such as magnetic skyrmions have attracted attention because of their intriguing topological nature and transport/optical properties due to emergent gauge fields. Such spin textures are stabilized by the Dzyaloshinskii-Moriya interaction (DMI) in noncentrosymmetric magnets and by the geometrical frustration or Fermi-surface instability in centrosymmetric magnets. Recently, an optical pulse has been found to be promising for creating and controlling spin textures on ultrafast time scales, albeit mainly in noncentrosymmetric magnets.

In this work, we consider the real-time dynamics in the ferromagnetic Kondo lattice model on the centrosymmetric triangular lattice [1]. We show that a static electric field and linearly polarized light can induce a transition from the ferromagnetic metallic state to the four-sublattice spin-scalar-chiral state even without the DMI. We found that these steady states are stabilized not by conventional field-induced DMI but by nonthermal electron distribution. Furthermore, the sign of scalar chirality can be controlled by circular polarization, and metastable magnetic skyrmions emerge after light irradiation.