Flexoelectric engineering of van der Waals ferroelectric CuInP2S6

Van der Waals layered CuInP2S6 (CIPS) is an ideal candidate for developing two-dimensional microelectronic heterostructures because of its room temperature ferroelectricity, although field-driven polarization reversal of CIPS is intimately coupled with ionic migration, often causing erratic and damaging switching that is highly undesirable for device applications. In this work, we develop an alternative switching mechanism for CIPS using flexoelectric effect, abandoning external electric fields altogether, and the method is motivated by strong correlation between polarization and topography variation of CIPS. Phase-field simulation identifies a critical radius of curvature around 5 mu m for strain gradient to be effective, which is realized by engineered topographic surfaces using silver nanowires and optic grating upon which CIPS is transferred to. We also demonstrate mechanical modulation of CIPS on demand via strain gradient underneath a scanning probe, making it possible to engineer multiple polarization states of CIPS for device applications.

Automated summary

In this study, an alternative switching mechanism for Van der Waals layered CuInP2S6 (CIPS) using the flexoelectric effect was developed. By engineering the topographic surfaces, strain gradient was created, allowing mechanical modulation of CIPS and the possibility of engineering multiple polarization states for device applications.