The directional transport of magnetic skyrmions under microwave magnetic fields, known as the skyrmion ratchet effect, offers a promising approach for driving skyrmions in materials with poor electrical conductivity. While ratchet effects affected by disorders, biharmonic magnetic fields, and biased microwave fields have been widely discussed, the ratchet effect of magnetic skyrmions in systems with anisotropic Dzyaloshinskii-Moriya interaction (DMI) has not been investigated yet. In this work, we investigate the ratchet motion of skyrmions driven by a biharmonic magnetic field in systems with anisotropic DMI. Based on micromagnetic simulations, we demonstrate that anisotropic DMI effectively modulates the velocity and direction of skyrmion motion. Moreover, by inducing skyrmion deformation and altering its symmetry, the anisotropic DMI can lead to either nearly isotropic or highly anisotropic ratchet motion of skyrmions. Specifically, the skyrmion can exhibit identical ratchet velocities along different directions, or its motion can be confined to a specific direction, enabling highly direction-selective behavior. Based on the analysis of the frequency spectrum and the analytical theory, we attribute such directional anisotropy effects to the combined contributions of two factors, the anisotropic mass term and variation in the damping oscillation. These findings provide further insight into precise control of skyrmion motion based on the ratchet effect in insulating systems.

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• Magnetization dynamics
• Skyrmions
• Transport phenomena
• Microwave techniques
• Thiele equation