Flexible ferroelasticity in monolayer PdS2: a DFT study

Abstract

As an unusual mechanical response, the ferroelastic phenomenon in two-dimensional materials has been reported both experimentally and theoretically in recent years. Here, we present the theoretical findings of ferroelastic switching in monolayer PdS₂. We demonstrate four types of PdS₂ allotropes, showing excellent ferroelasticity with low ferroelastic barriers and strong switching signals. The ferroelastic transitions in monolayer PdS₂ include the lattice rotation in penta-α PdS₂, the transformation between penta-α PdS₂ and penta-β PdS₂, the transformation between penta-α PdS₂ and penta-γ PdS₂, the transformation between penta-β PdS₂ and penta-γ PdS₂, the transformation between penta-α PdS₂ and δ PdS₂, and the lattice rotation in δ PdS₂. The ferroelastic transitions between these four allotropes have revealed the flexible ferroelasticity in monolayer PdS₂. Specifically, the flexible switching in PdS₂ allotropes may efficiently control the anisotropic transport of electrons. Thus, the presence of these outstanding mechanical properties endows PdS₂ with great potential for applications in next-generation shape memory devices.