Structural Transition in Few-Layer Group-IV Monochalcogenides Induced by Mechanical Forces

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Group IV monochalcogenides are theoretically predicted to possess multiferroic properties, including ferroelectricity and ferroelasticity, at room temperature.
• Experimental investigation into the ferroelasticity of these materials remains limited.

Purpose of the Study:

• To theoretically report and experimentally investigate the ferroelastic properties of few-layer tin selenide (SnSe).
• To demonstrate the multiferroic behavior in SnSe by combining ferroelectric and ferroelastic characteristics.

Main Methods:

• Theoretical first-principles calculations to analyze strain-dependent second-harmonic generation (SHG) response.
• Experimental polarization-resolved SHG measurements on few-layer SnSe flakes to determine in-plane polarization.
• Observation and confirmation of force-induced structural transitions using SHG analysis.

Main Results:

• Ferroelastic properties were theoretically predicted and experimentally observed in few-layer SnSe.
• In-plane polarization of SnSe was identified along the armchair direction via SHG measurements.
• A force-induced structural transition, indicative of ferroelastic or partial ferroelastic switching, was confirmed in SnSe flakes.

Conclusions:

• Few-layer SnSe exhibits multiferroic behavior, integrating ferroelectric and ferroelastic properties.
• Experimental evidence supports ferroelastic switching in SnSe, driven by applied force.
• The findings open avenues for exploring novel electronic and multiferroic applications of SnSe.