Room temperature in-plane ferroelectricity in van der Waals InSe.

Van der Waals (vdW) assembly of layered materials is a promising paradigm for creating electronic and optoelectronic devices with novel properties. Ferroelectricity in vdW layered materials could enable nonvolatile memory and low-power electronic and optoelectronic switches, but to date, few vdW ferroelectrics have been reported, and few in-plane vdW ferroelectrics are known. We report the discovery of in-plane ferroelectricity in a widely investigated vdW layered material, β'-InSe.

Density functional theory computational study of ferroelectricity and piezoelectricity in BaTiO/PbTiO (0 1 1) superlattices.

The structure, ferroelectricity (FE), and piezoelectricity of epitaxial BaTiO/PbTiO (BTO/PTO) (0 1 1) superlattices are studied using density functional theory calculations. Our results show that compressive strain arising from the SrTiO (0 1 1) substrate stabilizes the (BTO) /(PTO) (0 1 1) superlattices in orthorhombic phase with the FE polarization along [0 1 1] direction. Tuning the BTO contents significantly changes the structural, ferroelectric and piezoelectric properties.