Layer-dependent ferroelectricity in 2H-stacked few-layer α-In₂Se₃

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Two-dimensional (2D) van der Waals materials display unique layer-dependent physical properties.
• Ferroelectricity in 2D materials is a key area of research for novel electronic devices.

Purpose of the Study:

• To investigate the ferroelectric polarization behavior in few-layer 2H-stacked α-In2Se3 nanoflakes.
• To explore the influence of layer number on ferroelectric properties.

Main Methods:

• Piezoresponse Force Microscopy (PFM) to characterize ferroelectric polarization.
• Density Functional Theory (DFT) calculations to understand the underlying mechanisms.

Main Results:

• Observed a striking even-odd layer dependent oscillation in ferroelectric polarization.
• Odd-layer (OL) samples showed larger out-of-plane (OOP) polarization than even-layer (EL) samples.
• Demonstrated a tunable negative differential resistance induced by polarization switching.

Conclusions:

• The even-odd ferroelectric effect in α-In2Se3 arises from the interplay between in-plane (IP) and OOP polarization and the specific 2H-stacking structure.
• This finding enriches the understanding of layer-dependent phenomena in 2D materials and suggests potential for novel electronic applications.