Manipulating optical and electronic properties through interfacial ferroelectricity

Interfacial ferroelectricity is a recently established mechanism for generating spontaneous reversible electric polarization, arising from the charge transfer between stacked van der Waals layered atomic crystals. It has been realized in both naturally formed multilayer crystals and moiré superlattices. Owing to the large number of material choices and combinations, this approach is highly versatile, greatly expanding the scope of ultrathin ferroelectrics. A key advantage of interfacial ferroelectricity is its potential to couple with preexisting properties of the constituent layers, enabling their electrical manipulation through ferroelectric switching and paving the way for advanced device functionalities. This review article summarizes recent experimental progress in interfacial ferroelectricity, with an emphasis on its coupling with a variety of electronic properties. After introducing the underlying mechanism of interfacial ferroelectricity and the range of material systems discovered to date, we highlight selected examples showcasing ferroelectric control of excitonic optical properties, Berry curvature effects, and superconductivity. We also discuss the challenges and opportunities that await further studies in this field.