Perspective: Domain wall nanoelectronics

Abstract

Ferroelectric domain walls are two-dimensional interface structures with electrical conductivities that can be many orders of magnitude greater than the matrix they surround. They can be p- or n-type, metallic, and even superconducting. They necessarily exist in networks, where each wall must terminate either at another wall or at a bounding surface. In that sense, they form ready-made electrical circuits, only needing external contacts and connections to power sources. Crucially, walls can be created, moved, and annihilated by externally applied fields and, thus, wall networks are completely reconfigurable. This microstructural malleability suggests exciting possibilities for dynamic domain wall circuitry, which can be configured for one purpose in one instant, only to be completely reconfigured for a different purpose in the next. In this Perspective article, we will summarize the physics responsible for domain wall conduction, focusing on the effects of apparent polar divergence. We will present progress made to date, in the site-specific injection and controlled motion of domain walls, and discuss the kinds of devices realized so far (such as binary memory, memristors, p–n junctions, diodes, transistors, logic gates, and artificial synapses) that either rely on domain wall conducting conduits or can be made by controlling wall morphology. Challenges and needs for developing meaningful technology, based on domain walls, will also be explored.