Temperature-Dependent Magnetization Switching in FeGd Ferrimagnets

Laser-induced magnetization switching in GdFe ferrimagnets strongly depends on the pulse duration. To gain insight into the ferrimagnetic switching process, Landau–Lifshitz–Gilbert (LLG) spin dynamic modeling is performed at an atomistic-level with two sub-lattice systems. The switching dynamics triggered by laser pulses can be considered as two stages: Demagnetization stage by the laser pulse heating and re-magnetization at the cooling down stage after the pulse impulsion. By tuning the laser pulse duration, the intensity of demagnetization can be well controlled, by which the subsequent magnetization switching during the cooling process can be obtained. The simulation results indicate that the occurrence of the transient ferromagnetic-like (TFL) state is necessary during the magnetization switching process. Furthermore, the thermal temperature and heating time play an important role for the ferrimagnetic switching. In the overheating region, the random switching behavior appears because the TFL state is uncontrollable.