Ultrafast domain wall motion in a polar oxide nanostructure

Domain wall propagation in conventional ferroelectric materials under an electric field is often hindered by disorder and hence its velocity is orders-of-magnitude lower than the speed of sound. The recent discovery of quasi-long-ranged topological polar textures in oxide superlattices — such as polar vortices and skyrmions — offers an alternative platform to investigate domain wall motion in ferroelectrics, where atomic-scale disorder plays a minor role in nanotextures with characteristic size on the order of 10 nm. Here, we study the domain dynamics of polar textures in a PbTiO₃/SrTiO₃ superlattice using time-resolved electron diffraction and microscopy. Following photoexcitation, we observed a rapid suppression of the polar texture within 1 ps, where textures within one domain are preferentially melted. The selective melting leads to a fast expansion of the other domain, whose boundary propagates near the sound speed characteristic of the collective motion of nanotextures. The spatiotemporal visualization of this ultrafast domain wall motion not only yields insights into the fundamental limit of its velocity in ferroelectric systems but also introduces new possibilities for memory devices based on topological polar textures.