Intrinsic Ferroelectric Switching in Two-Dimensional α-In₂Se₃

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) ferroelectric semiconductors are key for advanced nanoelectronics.
• α-Indium Selenide (α-In₂Se₃) is a 2D ferroelectric with vertical polarization, but its in-plane properties are debated.

Purpose of the Study:

• To resolve conflicting experimental and theoretical findings on α-In₂Se₃'s ferroelectricity.
• To elucidate the domain switching mechanisms in monolayer α-In₂Se₃.

Main Methods:

• Combined experimental characterizations using piezoresponse force microscopy and symmetry analysis.
• Deep-learning-assisted large-scale molecular dynamics simulations.

Main Results:

• Conclusively dismissed claims of in-plane ferroelectricity in single-domain α-In₂Se₃.
• Revealed novel atomistic mechanisms for vertical polarization switching.
• Demonstrated that 1D domain walls move via avalanche dynamics under both out-of-plane and in-plane fields.
• Characterized domain wall velocity using a universal creep equation with a distinct dynamical exponent of 2.

Conclusions:

• Rectified the misunderstanding of in-plane ferroelectricity in α-In₂Se₃.
• Quantitative characterization of domain wall dynamics provides crucial data for 2D ferroelectric applications and fundamental understanding.