Interface engineering in ferroelectric films

The switchable polarization of ferroelectric materials and their coupling to external fields provide the physical basis for their applications in storage and sensing and for constructing functional interfaces. This perspective outlines ferroelectric thin-film interface engineering, a key strategy to overcome nanoscale limitations and create functionalities. We focus on heterointerfaces and homogeneous interfaces: at heterointerfaces, mechanisms such as charge transfer and strain can give rise to emergent states, including two-dimensional electron gases; homogeneous interfaces, embodied by domain walls, possess functionalities such as conductivity and topological protection that originate from their local polarization configuration and charge screening. Furthermore, we discuss the dynamic external field control of these interfaces, highlighting that the intrinsic coupling of multiple degrees of freedom presents both a challenge in the form of crosstalk and an opportunity for synergistic control. Looking forward, a combination of predictive theory, atomic-scale fabrication, and advanced in situ characterization promises to enable the on-demand design of functionality, making ferroelectric interfaces a core driving force for next-generation information technologies.