  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 Schr\"odinger equation combined with the
Landau-Lifshitz-Gilbert equation, we find finite winding number and chirality,
which implies emergence of topological chiral spin textures. These observations
are reproduced by a calculation where 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.
