Fig. 12: Broken inversion symmetry and induced ferroelectricity in the tricolor perovskite superlattice.

Schematic plots demonstrate how the spatial inversion is broken by the number of species (colors) included in the superlattice. a The individual interface dipoles and the b overall interface dipole as a function of electric displacement field in bicolor BaTiO3/SrTiO3 bicolor superlattice. c The overall interface dipole as a function of electric displacement field in tricolor BaTiO3/SrTiO3/CaTiO3 superlattices.