Harness of room-temperature polar skyrmion bag in oxide superlattice

Skyrmion bag is a higher-order skyrmion-based topological structure that can be used to reduce the risk of data loss in memory devices. It consists of an outer skyrmion wall and several inner skyrmions with opposite polarities. While skyrmion bags have been observed in ferromagnetic materials and liquid crystals, creating a polar skyrmion bag has proven challenging. Herein, we report the creation, evolution, and destruction of a polar skyrmion bag in a ferroelectric/dielectric oxide superlattice. The creation of a polar skyrmion bag is facilitated by applying an electric field pulse through a charged tip, which could be eliminated by changing the field direction. We also discover that the topological charge inside a polar skyrmion bag can be manipulated in situ by adjusting the magnitude of the applied potential. Through combined experimental observations and theoretical calculations, we have gained new insights into multipolar boundaries and identified promising prospects for future high-density, scalable, robust memory and low-loss nanoelectronics devices.