Nonreciprocity of Domain-Wall Motion Induced by Interlayer Dzyaloshinskii-Moriya Interaction.

The Dzyaloshinskii-Moriya interaction (DMI) stabilizes chiral spin textures, making it essential for spintronic devices. Interlayer DMI is an antisymmetric exchange interaction between separated magnetic layers. However, its influence on spin-orbit torque-driven domain wall motion, vital for racetrack-memory devices, remains unclear. Here, we introduce interlayer DMI into Pt/Co/Pt/Ir/Pt/Co/Pt multilayers with synthetic ferromagnetic or antiferromagnetic coupling and examine domain wall motion. Varying the azimuthal angle between the interlayer DMI vector and the current, we demonstrate nonreciprocal domain wall motion: the velocity differs for current parallel versus antiparallel to the DMI vector and depends on domain wall polarity. The nonreciprocity peaks when the DMI vector is parallel or antiparallel to the current, while symmetric motion appears when perpendicular. Micromagnetic simulations confirm it arises from the symmetry-breaking effect of interlayer DMI. These findings show interlayer DMI adds a dimension to domain wall control, offering a design principle for future racetrack-memory devices.