Photoinduced topological spin texture in a metallic ferromagnet

Photoinduced nonequilibrium spin structure is examined in the double-exchange model, in which itinerant electrons couple with localized spins through the ferromagnetic Hund coupling. In particular, we focus on the transient spin structure from the initial ferromagnetic metallic state to the steady antiferromagnetic ordered state reported in [Phys. Rev. Lett. 119, 207202 (2017)]. By solving the Schrödinger equation combined with the Landau–Lifshitz–Gilbert equation, we find the finite winding number and chirality, which implies the emergence of topological chiral spin textures. These observations are reproduced by a calculation in which the spin dynamics after sudden quench of the chemical potential are examined in larger clusters. A possible mechanism of the topological spin texture in the transient dynamics is discussed.