Influence of the magnetic field sweeping rate on magnetic transitions in synthetic ferrimagnets with perpendicular anisotropy

The evolution of the switching field between stable states in MgO/CoFeB/Ta/CoFeB/MgO/GaAs and Pt/Co/Ir/Co/Pt/Ta/SiO2 synthetic ferrimagnets with perpendicular anisotropy as a function of the magnetic field sweeping rate (MFSR) of 0.1–104 Oe/s has been studied. The most significant effect of the MFSR is an inversion of the interstate transition sequence. In the MgO/CoFeB/Ta/CoFeB/MgO/GaAs heterostructure, the increase in MFSR switches the dominant mechanism of magnetization reversal from propagation of domain walls to a nucleation of reversed magnetization areas. In Pt/Co/Ir/Co/Pt/Ta/SiO2, the MFSR affects the final domain state of the transition, starting from the initial antiparallel configuration of the synthetic ferrimagnet.