  Two-dimensional (2D) van der Waals (vdW) magnets represent one of the most
promising horizons for energy-efficient spintronic applications because their
broad range of electronic, magnetic and topological properties. Of particular
interest is the control of the magnetic properties of 2D materials by
femtosecond laser pulses which can provide a real path for low-power
consumption device platforms in data storage industries. However, little is
known about the interplay between light and spin properties in vdW layers.
Here, combining large-scale spin dynamics simulations including biquadratic
exchange interactions and wide-field Kerr microscopy (WFKM), we show that
ultrafast laser excitation can not only generate different type of spin
textures in CrGeTe$_3$ vdW magnets but also induce a reversible transformation
between them in a toggle-switch mechanism. Our calculations show that
skyrmions, anti-skyrmions, skyrmioniums and stripe domains can be generated via
high-intense laser pulses within the picosecond regime. The effect is tunable
with the laser energy where different spin behaviours can be selected, such as
fast demagnetisation process ($\sim$250 fs) important for information
technologies. The phase transformation between the different topological spin
textures is obtained as additional laser pulses are applied to the system where
the polarisation and final state of the spins can be controlled by external
magnetic fields. We experimentally confirmed the creation, manipulation and
toggle switching phenomena in CrGeTe$_3$ due to the unique aspect of
laser-induced heating of electrons. Our results indicate laser-driven spin
textures on 2D magnets as a pathway towards ultrafast reconfigurable
architecture at the atomistic level.
