Two-dimensional ferroelastic semiconductors in single-layer indium oxygen halide InOY (Y = Cl/Br).

Two-dimensional ferroelastic materials have triggered tremendous interest for applications in nonvolatile memory devices. Here using first-principles calculations, we identify a novel class of two-dimensional ferroelastic materials, single-layer InOY (Y = Cl/Br). The ferroelasticity in single-layer InOY shows a moderate switching barrier and high reversible strain, which are promising for practical applications in nonvolatile memory. Meanwhile, single-layer InOY is a semiconductor with an indirect band gap. The unique combination of being a semiconductor with ferroelastic behaviors would be beneficial for the integration of functional nonvolatile memories into nanocircuits. Moreover, both systems can readily be exfoliated from their layered bulks due to the weak interlayer interactions. These intriguing behaviors suggest the high potential of single-layer InOY for practical memory device applications.