Ferroelectric Domains Engineering in 2D Van Der Waals Ferroelectric α-In2Se3 Via Flexoelectric Effect

2D) Van der Waals ferroelectrics offer the opportunity for developing novel nanoelectronics devices. For device applications, it is necessary to generate controllable ferroelectric polarization domains and achieve non-destructive polarization switching. However, it is very challenging to use the electric field to manipulate the domain state of ultra-thin ferroelectric film due to the large leakage current and even electric breakdown. Here, the flexoelectric effect on the manipulation of polarization states at bending alpha-In2Se3 flakes is explored via piezoresponse force microscopy (PFM). By introducing patterned Si trench substrates, the stripe micron-scale ferroelectric domains with alternating arrangements of the out of-plane polarization in the curved alpha-In2Se3 are observed. It is found that the polarization at the bending region of alpha-In2Se3 can be directly reversed by the large flexoelectric field. The controllable mechanical modulation of alpha-In2Se3 ferroelectric domains opens up potential applications of ferroelectrics in strain engineering functional devices.