Uniaxial Strain-Dependent SHG: Experimental and Theoretical Study of Ferroelastic Switching in AB-SnSe Five-Layer Structures

Redhwan Moqbel^1,2,3*, V.K.Ranganayakulu¹, Raman Sankar¹, Min-Nan Ou¹, Chi-Cheng Lee⁴, Kung-Hsuan Lin¹

¹Institute of Physics, Academia Sinica, Taipei, Taiwan
²Department of Physics, National Taiwan University, aipei 10617, Taiwan
³Nano-Science and Technology Program Taiwan International Graduate Program, Academia Sinica, Taipei 11529, Taiwan
⁴Department of Physics, Tamkang University, Tamsui, New Taipei 251301, Taiwan

* Presenter:Redhwan Moqbel, email:redhwanmoqbel@gate.sinica.edu.tw

Multiferroic materials exhibit both ferroelectric and ferroelastic behaviors and have garnered significant attention in nanotechnology applications. One such material that shows potential in this regard is SnSe. Monolayer and a few-layer with odd number structures of AB-SnSe demonstrate multiferroic properties at room temperature, offering significant promise for future flexible nanotechnology applications. This study focuses on investigating the second-harmonic generation (SHG) in a five-layer SnSe sample, fabricated via mechanical exfoliation onto a PDMS substrate with controlled uniaxial strain. The SHG polar patterns exhibit noticeable variations in intensity as the applied strain on PDMS, with SnSe atop. Moreover, ferroelastic switching is observed in the five-layer SnSe structure. Theoretical analysis using First Principles Calculation based on (DFT) is employed to predict SHG spectra and strain-dependent SHG behaviors across monolayer, three-layer, and five-layer SnSe structures with AB stacking. The theoretical predictions qualitatively align well with the experimental findings, underscoring the influence of strain on the SHG properties of SnSe.

Keywords: SHG, ferroelectric SnSe Few Layers, Strain dependent, Ferroelastic Switching