The spin dynamics triggered by an ultrashort optical excitation can lead to a variety of behaviors depending on the
specific spin and electronic structure of the material. In metallic films, electron-quasiparticles (phonons and magnons)
interactions takes place on sub-picosecond timescale and demagnetization is established within 100 fs. In half-metal
oxides, spin dynamics is much slower (100 ps) due to the inhibition of spin-flip processes. Furthermore, the dynamics of
magnetic anisotropies can be exploited to control the magnetization in ferromagnets. Optically-induced reversible
switching of the magnetization has been recently demonstrated in thin magnetic layers on the 100 picoseconds timescale.