Multistate Switching of a Single Polar Skyrmion Bubble.

Polar skyrmions, as noncollinear polarization textures, have attracted a considerable amount of attention so far because of their novel physical properties. Multistate switching of polar skyrmions is paramount for brain-inspired computing applications, but experimental realization remains challenging because of the inaccessibility of feasible boundary conditions. Here, we explore in situ electrical switching of CuInP2S6-based polar skyrmion bubbles with respect to resistance states on silicon substrates. Because of Cu+ mediation and the large size of CuInP2S6 skyrmions, we can electrically manipulate the boundary conditions and create a series of intermediate skyrmion states. Consequently, we acquire eight nonvolatile resistance states from a single skyrmion bubble, in which information storage density far exceeds that of the current hard drives. On the basis of these devices, we build skyrmion-based solid neurons and simulate spiking neural networks with a recognition accuracy of 98%. Our study shows the uncharted application prospects of polar skyrmions in silicon-based, high-density memory hardware and neuromorphic computing.