Creation of Independently Controllable and Long Lifetime Polar Skyrmion Textures in Ferroelectric-Metallic Heterostructures.

Topological textures like vortices, labyrinths, and skyrmions formed in ferroic materials have attracted extensive interest during the past decade for their fundamental physics, intriguing topology, and technological prospects. So far, polar skyrmions remain scarce in ferroelectrics as they require a delicate balance between various dipolar interactions. Here, it is reported that PbTiO thin films in a metallic contact undergo a topological phase transition and hold a broad family of skyrmion-like textures including Q = ±1 skyrmions, multiple π-twist target skyrmions, and skyrmion bags, with independent controllability, analogous to those reported in magnetic systems. Weakly-interacted skyrmion arrays with a density over 300 Gbit/inch are successfully written, erased, and read out by local electrical and mechanical stimuli of a scanning probe. Interestingly, in contrast to the relatively short lifetime (<20 hours) of the normal skyrmions, the multiple π-twist target skyrmions and skyrmion bags show topology-enhanced stability with a lifetime of over two weeks. Experimental and theoretical analysis implies the heterostructures carry electric Dzyaloshinskii-Moriya interaction mediated by oxygen octahedral tiltings. The results demonstrate ferroelectric-metallic heterostructures as fertile playgrounds for topological states and emergent phenomena.