Photoinduced topological spin texture in a metallic ferromagnet

TL;DR

This paper investigates how photoexcitation induces topological chiral spin textures in a metallic ferromagnet, revealing transient topological states with finite winding numbers through numerical simulations.

Contribution

It demonstrates the emergence of topological spin textures during nonequilibrium dynamics in a double-exchange model, a novel insight into photoinduced topological magnetic phenomena.

Findings

Finite winding number and chirality observed in transient states

Topological spin textures emerge after photoexcitation

Results reproduced in larger cluster simulations

Abstract

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.