Domain wall creep motions depending on the type and thickness of the upper layer in Co-based magnetic multilayer films

In this study, we investigated the changes in magnetic domain dynamics as a function of the thickness of the upper Pt and Cu layers in Pt/Co/Pt and Pt/Co/Cu structures using a magneto-optical Kerr microscope capable of real-time domain change observation. Interestingly enough, it was found that domain reversal in all samples exhibited circular domain wall motion. In addition, the domain wall velocity as a function of the magnetic field was consistent with predictions based on a theoretical model assuming domain wall creep motion. The domain dynamics varied substantially with the upper layer’s thickness, depending on whether Pt or Cu was used. These variations were attributed to changes in magnetic anisotropy and microscopic pinning properties influenced by the type and thickness of the upper layer.