Anisotropic domain wall dynamics in perpendicularly magnetized Pt/Co/Ta multilayers with a lateral symmetry breaking

Abstract Magnetic racetrack devices are promising candidates for next-generation spintronic memories formed in ferromagnet/heavy metal thin-film systems exhibiting perpendicular magnetic anisotropy. Information is stored in chiral Néel-type domain walls (DWs) stabilized by interfacial Dzyaloshinskii–Moriya interaction (DMI). Therefore, understanding DW dynamics is essential for the development of practical racetrack memory devices. Here, we study the magnetic field driven DW dynamics in a perpendicularly magnetized Pt/Co/Ta multilayer with a lateral symmetry breaking induced by a wedged Co layer. Consequently, we demonstrate that DW motion velocities between directions parallel and perpendicular to the Co thickness gradient are anisotropic, which becomes more pronounced with decreasing Co thickness. In contrast, the DW velocities are almost isotropic at thick Co side. We reveal that the anisotropy is caused by the in-plane magnetocrystalline anisotropy field and effective field of interfacial DMI. These findings enhance the understanding of chiral DWs and support spintronic device development.