The CdTiO/BaTiO superlattice interface from first principles.

The oxide interface has been studied extensively in the past decades and exhibits different physical properties from the constituent bulks. Using first-principles electronic structure calculations, we investigated the interface of CdTiO/BaTiO (CTO/BTO) superlattice with ferroelectric BaTiO. In this case, the conduction bands of CdTiO are composed of Cd-5s orbitals with low electron effective mass and nondegenerate dispersion, and thus expected to have high mobility. We predicted a controllable conductivity at the interface, and further analyzed how the polarization direction and strength affect the conductivity. We also explored the relationship between two components: thickness and polarization. Intriguingly, the total polarization in CTO/BTO might be even larger than that of ferroelectric bulk BaTiO. Therefore, we found a way to maximize the superlattice polarization by increasing the fraction of the CdTiO layers, based on the interesting dependence of the total polarization and CTO/BTO ratio.