Current-driven magnetic skyrmion diodes controlled by voltage gates in synthetic antiferromagnets

Magnetic skyrmions, as promising candidates in various spintronic devices, have been widely studied owing to their particle-like properties, nanoscale size, and low driving current density. Here, we numerically and theoretically investigate the dynamics of current-driven skyrmion passing through a voltage gate in a synthetic antiferromagnetic racetrack. It is found that the critical current required for skyrmion to pass through the voltage gate positively is much less than that for skyrmion to pass through the gate negatively. Furthermore, we systematically study the linear dependence of the minimum velocity of skyrmion on the driving current density and perpendicular magnetic anisotropy (PMA) gradient, and the calculation results are quite consistent with the simulation results. Finally, we find that the variation of the PMA energy with the position of skyrmion can help us to compare the magnitude of resistance force when the skyrmion passes through different voltage gates. Our results can be beneficial for the design and development of skyrmion diodes.