Ultrafast spin dynamics across compensation points in ferrimagnetic GdFeCo: The role of angular momentum compensation

Using an all-optical pump and probe technique, we have investigated the temperature dependence of the ultrafast magnetic response in a ferrimagnetic amorphous GdFeCo thin film. When the temperature of the sample approaches the angular momentum compensation point, both frequency and the Gilbert damping parameter of the magnetization precession increase significantly. In addition, the high-frequency exchange mode softens and becomes observable. The observed high-speed and strongly damped spin dynamics in the vicinity of the compensation of the angular momentum is ideal for ultrafast ringing-free precessional switching in magnetic and magneto-optical recording.