We report on a theoretical study of thermal magnetization switching induced by nanosecond electric current pulse using Lagrangian formalism based on the Landau–Lifshitz–Gilbert equation. The parameters for modeling are obtained from the measurements of the anomalous Hall resistance at different probe currents. We obtain the switching diagrams, analyze how the switching rate depends on the pulse parameters and the applied magnetic field, and find the optimal set of values such as orientation of the field, electric pulse duration, and energy consumption. We find that the magnetization switching is particularly efficient near the compensation point, where a decrease in the magnetization of the rare-earth sublattices by 10% or less can lead to reversal of net magnetization.

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We investigate the Hf/GdFeCo bilayer with the MgO cap layer for both rare earth (RE)-rich and transition metal (TM)-rich configurations of the ferrimagnetic sublattice in the presence of the perpendicular field. We study the coercivity using the anomalous Hall effect (AHE) technique by multiple measurements on the same sample. In the first set of measurements and at low electric currents, coercivity sharply drops because of the oxygen diffusion at the interface between MgO and GdFeCo when the AHE probe current is applied. During the subsequent measurements on the RE-rich sample, we observe a moderate decrease in coercivity at low currents and the coercivity increases in a high current range. Such nonlinear dependence of coercivity on electric current can be explained by the competing interplay of the spin–orbit torque (SOT) and the Joule heating effects. On the other hand, for the TM-rich case, the SOT effect is observed over a widely applied current range.

It is shown using the technique of double high-speed photography that an external magnetic field triggers the motion of a GdFeCo domain wall with a velocity up to 1.2 km/s. The domain wall velocity increases and levels off with an increase in the amplitude of the driving magnetic-field pulse. In contrast to the earlier experiments on iron ferrites, no influence of femtosecond laser pulses on the domain wall dynamics has been observed, even when the pump pulse energy is sufficient for magnetization reversal.

We report of a theoretical model for calculating the H-T phase diagrams of a rare-earth ferrimagnet, taking into account anisotropies originated by both magnetization sublattices' and by the surface. The possibility of an exchange spring formation due to surface anisotropy is considered. This situation is realized in heterostructures containing a ferrimagnet and a heavy metal. We derive the stability lose lines of the collinear phase from the free energy of the two sublattice ferrimagnet. We numerical calculate the magnetic phase diagrams for the cases when the magnetic field applied along and perpendecular to the easy axis. We demonstrate that tricritical point down at the low field range due to surface anisotropy effect. Moreover, the line of the first order phase transition between angular and collinear phases reduces due to surface anisotropy. In the case when magnetic field is applied perpendicular to the easy axis we show the possibility of the first order phase transition between two collinear phases in contrast to the phase diagram without surface anisotropy.