  Laser-induced ultrafast demagnetization is a phenomenon of utmost interest
and attracts significant attention because it enables potential applications in
ultrafast optoelectronics and spintronics. As a spin-orbit coupling assisted
magnetic insulator, $\alpha$-$RuCl_3$ provides an attractive platform to
explore the physics of electronic correlations and related unconventional
magnetism. Using time-dependent density functional theory, we explore the
ultrafast laser-induced dynamics of the electronic and magnetic structures in
$\alpha$-$RuCl_3$. Our study unveils that laser pulses can introduce ultrafast
demagnetizations in $\alpha$-$RuCl_3$, accompanied by an out-of-equilibrium
insulator-to-metal transition in a few tens of femtoseconds. The spin response
significantly depends on the laser wavelength and polarization on account of
the electron correlations, band renormalizations and charge redistributions.
These findings provide physical insights into the coupling between the
electronic and magnetic degrees of freedom in $\alpha$-$RuCl_3$ and shed light
on suppressing the long-range magnetic orders and reaching a proximate spin
liquid phase for two-dimensional magnets on an ultrafast timescale.
