The nature of domain wall (DW) dynamics in synthetic ferrimagnetic multilayers composed of $\mathrm{Pt}\left|\mathrm{Co}\right|\mathrm{Tb}|\mathrm{Al}$ for different Tb thickness has been explored, focusing on the underlying pinning parameters, and on the different regimes of DW dynamics driven by spin-orbit torques (SOTs). We find that because of the AFM coupling between Co and Tb, the magnetic moment of Tb increases with Tb thickness resulting in a reduced saturation magnetization and an enhanced depinning field. The DW disorder interaction is found to vary weakly with the AFM coupling between Co and Tb, while the complete withdrawal of the Tb layer strongly increases the anisotropy and the DW pinning. Furthermore, we propose an approach to measure effective SOTs by comparing depinning transitions in current- and field-induced DW motion. This research reveals insights into DW dynamics in coupled AFM systems, highlighting enhancements in mobility through optimized SOTs and pinning landscapes.

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• Dynamic critical phenomena
• Magnetization dynamics
• Spin torque
• Spintronics