Strain-Reshaped Mexican-Hat-Like Energy Landscape Enables Ferroelastic Variant Selection in 2D β'-In₂Se₃.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Two-dimensional β -In2Se3 exhibits complex ferroelectric, antiferroelectric, and ferroelastic properties.
• The precise origin of strain-induced ferroelastic switching in this material is not fully understood.

Purpose of the Study:

• To elucidate the microscopic mechanisms behind strain-driven ferroelastic switching in 2D β -In2Se3.
• To investigate how mechanical strain influences the material's potential energy landscape and polarization variants.

Main Methods:

• First-principles calculations were employed to model the behavior of β -In2Se3 under mechanical strain.
• Analysis focused on the potential energy landscape and the displacement of central-layer Se atoms (Se-CL).

Main Results:

• β -In2Se3 transitions from an unstable β phase via Se-CL displacement, following a Mexican-hat-like potential.
• Uniaxial strain breaks the rotational symmetry of this potential, creating a canyon-like landscape that dictates Se-CL displacement direction.
• This strain-induced symmetry breaking effectively controls the orientation of in-plane ferroelastic variants.

Conclusions:

• Strain directly modulates in-plane polarization variants by reshaping the potential energy landscape.
• The study reveals a key coupling between lattice distortion and domain switching in 2D ferroelastics.
• Findings suggest potential for advanced, strain-controlled, low-power 2D ferroic devices.