Ultrafast Laser‐Induced Magnetic Order Transitions and Control of Skyrmion in CrSCl Monolayer

Light–spin coupling is attractive for both fundamental physics and device applications, yet the microscopic link between ultrafast electronic excitation and the ensuing reshaping of exchange, anisotropy, and chiral interactions in two‐dimensional magnets remains insufficiently understood. Here, by combining first‐principles calculations, rt‐TDDFT with Ehrenfest nuclear dynamics, and atomistic spin‐model simulations, laser manipulation of skyrmion textures in a CrSCl monolayer is investigated, establishing a multiscale route for ultrafast topological spin control. Photoexcitation induces pronounced spin‐resolved charge redistribution and ultrafast demagnetization, and drives a transition of the magnetic order from ferromagnetic (FM) to ferrimagnetic (FiM) phase. This laser‐driven FM‐FiM conversion dynamically renormalizes the magnetic interaction parameters, thereby modulating the resulting topological response. Ultimately, ultrafast laser excitation enables programmable control over the skyrmion density, size, and topological charge within an experimentally accessible magnetic field range. These results offer a mechanism‐resolved route toward ultrafast, low‐dissipation engineering of chiral spin textures in two‐dimensional magnets.