Anisotropy and Slow Relaxation of the Anomalous Hall Effect in GdFeCo/Ir/GdFeCo Synthetic Ferrimagnets

In GdFeCo/Ir/GdFeCo synthetic ferrimagnets with perpendicular anisotropy, the dependence of the hysteresis loops of the anomalous Hall resistance and the characteristics of the loops on the angle between the magnetic field and the sample plane is obtained. The part of the anomalous Hall resistance corresponding to the spin–orbital torque is isolated. The field dependences of the resistance are sensitive to switching between the magnetic states of a two-layer ferrimagnet and repeat the shape of the magnetization hysteresis loop calculated taking into account the interlayer exchange interaction, crystal anisotropy, and Zeeman energy at different angles between the field and the normal to the sample plane. A slow (about 30 min) magnetic relaxation that is detected from the hysteresis loop of the spin–orbit torque is found for switching states of the heterostructure upon a sharp change in the orientation of the magnetic field with respect to the sample. Kerr microscopy shows slow variations in the spin–orbit torque after field reorientation, which are caused by specific domain dynamics inherent in two-layer samples.