Long-Range Bulk-Like Interlayer Dzyaloshinskii-Moriya Interaction Enables Stabilized 3D Magnetic Textures

As an antisymmetric exchange interaction, the Dzyaloshinskii-Moriya interaction (DMI) favors canted spin alignment and stabilizes chiral spin textures. However, the existing DMI effects, e.g., interfacial DMI, bulk DMI, and interlayer DMI, cannot achieve long-range characteristics and vertical chirality simultaneously, hindering the implementation of three-dimensional (3D) topological magnetic textures. Here, we first achieve a bulk-like interlayer DMI (BIL-DMI) effect in gradient magnetic multilayers by engineering in-plane (IP) and out-of-plane (OOP) symmetry breaking, which presents unprecedented long-range vertical chirality. The direction and magnitude of the BIL-DMI-induced IP/OOP DMI effective fields depend on the DMI gradient, and the OOP effective field exhibits exotically linear dependence on external magnetic fields, distinctly different from the existing saturation behaviors of interlayer DMI. Moreover, a continuum model is built to explain the mechanism of BIL-DMI and quantitatively describe the experimental observations. Based on the BIL-DMI, unique 3D transverse skyrmion/bimeron strings applicable to next-generation magnonic circuits are first stabilized in theory, which is unachievable relying on existing DMI effects. The discovery of BIL-DMI achieves access to a long-range version of IL-DMI through gradient engineering, providing a platform for the investigation and application of 3D topological magnetic textures.