Ultrafast multi-level control of sub-50 nm skyrmions in a Pd-intercalated van der Waals magnet.

Achieving ultrafast, multi-level control of nanoscale skyrmions offers a transformative route for advancing van der Waals spintronics towards high-speed, scalable neuromorphic computing applications. However, progress has been impeded by the relatively large skyrmion size (~100 nm) in existing van der Waals magnets and the lack of efficient control strategies. Here, we simultaneously address both challenges by combining atomic intercalation with femtosecond laser manipulation. Through Pd atomic intercalation into the van der Waals magnet Fe3-δGaTe2, we realize magnetic field-stabilized skyrmions with an average diameter of ~43 nm at room temperature, the smallest skyrmions reported in the van der Waals magnets to date. Mechanism analysis reveals that this size reduction arises from enhanced Dzyaloshinskii-Moriya interaction and suppressed Heisenberg exchange coupling. On this tailored platform, we further demonstrate femtosecond laser-induced ultrafast generation of 43 nm skyrmions with an ultra-low energy consumption of 0.6 pJ per skyrmion. Most importantly, by tuning the laser pulse number, we achieve deterministic, multi-level modulation of skyrmion density, enabling skyrmion-based optical neuromorphic computing with a simulated training accuracy of ~91%.