Role of interlayer interactions in the recovery of synthetic ferrimagnetic skyrmions in [Co/Gd/Pt]_n multilayers after cycling through the spin reorientation transition

Antiferromagnetic (AFM) skyrmions offer potential technological advantages for spintronic devices since the skyrmions are less prone to skyrmion Hall effects, and recent work also shows that large current-driven velocities are also possible. Here we use micromagnetic simulations to gain insight into a spin memory effect that was recently demonstrated experimentally for synthetic AFM skyrmion pairs in [Co/Gd/Pt]_n=10 multilayered thin films. The synthetic AFM skyrmion pairs form in the Co due to the perpendicular anisotropy and interfacial Dzyaloshinkii Moriya interactions (DMI) that arise at the Co/Pt interface and are mirrored in the Gd due to the AFM exchange coupling between the Co and Gd layers. The skyrmions are erased when the temperature is lowered below the spin reorientation temperature and then recovered on rewarming. The simulations show that the DMIs play an essential role in the observed spin memory effect. We also explore the role of intralayer interactions on the spin memory process and show that although the stray fields from the other repeat units can influence the complexity of the low temperature in-plane distributions, the spin memory effect remains robust.