Role of photonic angular momentum in all-optical magnetic switching

We report on the role of light's angular momentum in magnetic all-optical switching (AOS), which entails magnetization reversal resulting from ultrafast laser pulses applied to a magnetic structure. The magnetic system is comprised of a ferromagnetic thin film of Co/Pt, excited by femtosecond vortex beams of light carrying spin, orbital angular momentum, or a superposition of both. We find that AOS is predominantly driven by the spin angular momentum of light. The experimental findings suggest that the magnitude of topological charge and handedness of the orbital angular momentum of light do not play a significant role. These results improve our understanding of the basic interactions between magnetism and light, paving the way for further investigation and the creation of all-optical magnetic switching technologies.