  We study THz-driven spin dynamics in thin CoPt films with perpendicular
magnetic anisotropy. Femtosecond magneto-optical Kerr effect measurements show
that demagnetization amplitude of about $1\%$ can be achieved with a peak THz
electric field of $300$~kV/cm, and a corresponding peak magnetic field of
$0.1$~T. The effect is more than an order of magnitude larger than observed in
samples with easy-plane anisotropy irradiated with the same field strength. We
also utilize finite-element simulations to design a meta-material structure
that can enhance the THz magnetic field by more than an order of magnitude,
over an area of several tens of square micrometers. Magnetic fields exceeding
$1$~Tesla, generated in such meta-materials with the available laser-based THz
sources, are expected to produce full magnetization reversal via ultrafast
ballistic precession driven by the THz radiation. Our results demonstrate the
possibility of table-top ultrafast magnetization reversal induced by THz
radiation.
