Temperature dependence of the frequencies and effective damping parameters of ferrimagnetic resonance

Recent experiments on all-optical switching in GdFeCo and CoGd have raised the question about the importance of the angular momentum or the magnetization compensation point for ultrafast magnetization dynamics. We investigate the dynamics of ferrimagnets by means of computer simulations as well as analytically. The results from atomistic modeling are explained by a theory based on the two-sublattice Landau-Lifshitz-Bloch equation. Similarly to the experimental results and unlike predictions based on the macroscopic Landau-Lifshitz equation, we find an increase in the effective damping at temperatures approaching the Curie temperature. Further results for the temperature dependence of the frequencies and effective damping parameters of the normal modes represent an improvement of former approximated solutions, building a better basis for comparison to recent experiments.