Ostler, T.A.; Evans, R.F.L.; Chantrell, R.W.; Atxitia, U.; Chubykalo- Fesenko, O.; Radu, I.; Abrudan, R.; Radu, F.; Tsukamoto, A.; Itoh, A.; Kirilyuk, A.; Rasing, T.; Kimel, A.: Crystallographically amorphous ferrimagnetic alloys: Comparing a localized atomistic spin model with experiments. Physical Review B 84 (2011), p. 024407/1-9
We present a computational model of crystallographically amorphous ferrimagnetic alloys using a stochastic Landau-Lifshitz-Gilbert equation of motion for atomistic spins and an atomistic spin Hamiltonian with Heisenberg exchange. The spontaneous equilibrium magnetization is calculated and a comparison with a mean field model is made. The simulations show excellent agreement with experiments on GdFeCo using x-ray magnetic circular dichroism to determine the individual sublattice magnetizations. The calculated temperature dependence of the magnetization shows a polarization of the Gd sublattice leading to a common Curie temperature, in agreement with the experimental data. The intersublattice exchange is shown to be an important energy transfer channel for ultrafast dynamics.