  Generating and manipulating magnetic skyrmions at ultrafast time scales is
essential for future skyrmionbased racetrack memory and logic gate
applications. Using the atomistic spin dynamics simulations, we demonstrate the
nucleation of ultra-small field-free magnetic skyrmions in amorphous GdFeCo at
picosecond timescales by femtosecond laser heating. The ultrafast nature of
laser heating and subsequent cooling from a high-temperature state is crucial
for forming magnetic skyrmion. The magnon localization and magnon coalescence
are the key driving mechanisms responsible for stabilizing the magnetic
skyrmions at zero field conditions. The polarization and, hence, the
topological charge can be switched by exploiting the all-optical switching
observed in GdFeCo. The skyrmion sizes and numbers can be controlled by varying
pulse width and fluence of incident laser pulses. Applying an external magnetic
field provides an additional degree of freedom to tune the skyrmion radius
during the ultrafast optical creation of magnetic skyrmions. Our results
provide a detailed understanding of the ultrafast creation of magnetic
skyrmions using femtosecond laser pulses, a vital step in advancing
next-generation skyrmion-based memory technologies.
