Ferroelectric Domain Wall Warp Memristor

Domain walls are quasi-one-dimensional topological defects in ferroic materials, which can harbor emergent functionalities. In the case of ferroelectric domain wall (FEDW) devices, an exciting frontier has emerged: memristor-based information storage and processing approaches. Memristor solid-state FEDW devices presented thus far, however predominantly utilize a complex network of domain walls to achieve the desired regulation of density and charge state. Here, using epitaxial bismuth ferrite thin films as a prototype ferroelectric and advanced scanning probe microscopy and stroboscopic methods, we demonstrate controlled single-wall memristive behavior through deterministic electric field-driven conformal changes. Our design exploits memristive functionality through surface pinning of topological domain walls. That is, although the FEDW is constricted by the surface, it is free to twist in the thickness direction. The resulting vertical variation of FEDW morphology creates a complex interplay between surface-induced pinning and field-induced wall bending. This gives rise to metastable electronic transitions, and hence memristive attributes. Moreover, being a single FEDW memristor, once injected there is no need for repeated injection or erasure. Microscopic insight into device operation from phase field modeling indicates controllable warping of the wall, causing memristive conductivity changes. Our results reaffirm the promise of FEDWS for brain-inspired neuromorphic and in-memory computing applications based on integrated ferroelectric devices.