Photoinduced Ultrafast Magnetization Dynamics in Yttrium-Iron Garnet and Ultrathin Co Films

We report experimental studies on ultrafast laser-induced magnetization dynamics on a picosecond time scale in ultrathin Co/garnet heterostructures. We compare polarization-sensitive nonthermal dynamics in garnet triggered via photoinduced anisotropy with the thermal dynamics in 2 nm Co films. The influence of Gilbert damping on frequency of magnetization precession under an external magnetic field in a garnet film is described. Thermal demagnetization with a 0.81 ps characteristic time is in good agreement with a two-temperature model of electron-lattice coupling.