Electric Field Control of Interfacial Ferroelectric Switching in Twisted 2D Semiconductors

The stacking configuration of twisted 2D material plays a crucial role in determining their moiré electronic properties, such as strong correlation, quantum confinement, and ferroelectric behavior. Transitioning from one stacking configuration to another involves energy conversion, typically influenced by external interactions such as electric fields. In the case of a twisted-stacking transition metal dichalcogenide bilayer, there exist two commensurate domains with opposite interfacial ferroelectric polarizations. The atomic structure of the domain wall between these domains exhibits a strain gradient, which can respond to a vertical electric field through flexoelectric effects, thereby inducing a change in the stacking configuration. In this study, we demonstrate the ability to manipulate this domain wall by applying a local electric field using a scanning tunneling microscopy tip, thereby controlling the interfacial ferroelectric switching. This ability to control the stacking configuration of twisted 2D materials opens up possibilities for novel twist-stacked 2D devices that incorporate both structural and electronic moiré superlattices.