Skyrmion-based reconfigurable logic gates and diodes in a racetrack with hard magnetic material and a notch

Due to the good stability and high mobility, magnetic skyrmions are considered for information carriers in future racetrack memory and spintronic devices. Here, we study the effect of the barrier at the edges on the dynamics of skyrmions in the Co/Pt bilayer racetrack, where the barrier is induced by a higher perpendicular magnetic anisotropy due to the hard magnetic material attached to the racetrack edges. In particular, we study the dynamics of skyrmions in the racetrack with a rectangular notch on one side of the boundary barrier. We systematically investigate the effect of the boundary barrier on the longitudinal velocity of the skyrmion. Compared with the model with no boundary force, it is found that when the repulsive effect of the boundary barrier just overcomes the Magnus force, the longitudinal velocity of the skyrmion can be increased significantly. We also find that a rectangular notch at the edge can be used to enrich the dynamics of the skyrmion. Based on the dynamic behaviors of skyrmions, we realize the skyrmion-based logic AND, OR, NOT, NAND and NOR gates and the diode in the same racetrack. In particular, the logic NOT, NAND and NOR gates are implemented in a reconfigurable way. Our results may be helpful for understanding the dynamics of skyrmions and may contribute to the design of non-volatile spintronic devices with integrated multiple functions and ultra-low energy consumption.