Magnetic skyrmion, with its nanoscale and topological features, can be employed as an information storage medium and logic function device in next-generation spintronic systems, attracting a lot of interest. Among all skyrmion logic devices, reconfigurable skyrmion logic devices have attracted much attention because they can efficiently perform different operations with the least number of devices to create different logical functions or operations. In 2018, Luo et al.1 proposed reconfigurable skyrmion logic gates by adding voltage control terminals to H-type nanotracks.
This paper proposes a voltage-controlled reconfigurable skyrmion circular orbit logic gate in Fig1(f). The complete logic family is implemented based on our skyrmion logic gates, in which the trajectories of skyrmion are manipulated by various effects including skyrmion-edge repulsions and the voltage control of magnetic anisotropy (VCMA) effect. Fig.1(a) represents the unique orbital model, Fig.1(b)-(d) show the anisotropic energy regulated by the VCMA effect, and Fig. 1(e) shows the logic function realized by the potential energy well distribution that we studied before2. The above logic functions can be integrated into a single skyrmion device, reconfigured by controlling the terminal voltage, and reused by the circular track structure. The corresponding skyrmion state and motion trajectories are shown in Fig.2. Because of the scheme, every logic judgment necessitates the generation and destruction of the skyrmion, increasing the logic device's energy consumption. Furthermore, the current drive in this system will create Joule heat, which will have an impact on skyrmion stability.
1 S. Luo, M. Song and X. Li, Nano Letters., vol. 18, pp. 1180-1184 (2018). 2 L. Yang, F. Jin and W. Mo, IEEE Transactions on Magnetics., vol. 58, pp. 1-5 (2022).
Fig.1 (a) Geometric dimensions of the circular track. (b)and(c) Voltage-controlled magnetic anisotropy gradient by using wedge structure. (d) Magnetic anisotropic energy distribution in skyrmion multiplexing. (e) The arrangement of potential wells to realize logical functions. (f) Structure of a reconfigurable skyrmion logic gate with the circular track.
Fig.2 (a) State and conversion process of skyrmion on the device. (b) The trajectories of skyrmion on the device.