All-optical stochastic switching of magnetisation textures in Fe3Sn2

Abstract The all-optical control of magnetisation at room temperature broadens the scope of applications of spin degrees-of-freedom in data storage, spintronics, and quantum computing. Topological magnetic spin structures, such as skyrmions, are of particular interest due to their particle-like properties, small size and inherent stability. Controlling skyrmion states without strong magnetic fields or large current densities would create new possibilities for their application. In this work, we utilize femtosecond optical pulses to alter the helicity of the spin configuration in dipolar skyrmions formed in the kagome magnet Fe 3 Sn 2 in the absence of an external magnetic field and at room temperature. In situ Lorentz transmission electron microscopy is used to visualise the light-induced stochastic switching process of chiral Néel caps, while the internal Bloch component of the dipolar skyrmions remains unchanged. In addition to this switching process, we observe the interconversion between type I skyrmionic and type II bubble configurations depending on the external magnetic field and illumination conditions. To corroborate the spin states and the light-induced magnetisation dynamics, micromagnetic modelling and simulations of the resulting electron phase shift maps are conducted to elucidate the spin rearrangement induced by individual femtosecond optical pulses.