Predicting Polarization and Nonlinear Dielectric Response of Arbitrary Perovskite Superlattice Sequences

We carry out first-principles calculations of the nonlinear dielectric response of short-period ferroelectric superlattices. We compute and store not only the total polarization, but also the Wannier-based polarizations of individual atomic layers, as a function of the electric displacement field, and use this information to construct a model capable of predicting the nonlinear dielectric response of an arbitrary superlattice sequence. We demonstrate the successful application of our approach to superlattices composed of ${\mathrm{SrTiO}}_3$, ${\mathrm{CaTiO}}_3$, and ${\mathrm{BaTiO}}_3$ layers.

Figure 1

Dependence of layer polarizations on chemical environment for (a) BaO planes (relative to a BaO plane in bulk ${\mathrm{BaTiO}}_3$) and (b) ${\mathrm{TiO}}_2$ planes (relative to an average of ${\mathrm{TiO}}_2$ planes in bulk ${\mathrm{BaTiO}}_3$ and ${\mathrm{SrTiO}}_3$). $C$, $S$, $B$, and $T$ refer to CaO, SrO, BaO, and ${\mathrm{TiO}}_2$ layers, respectively. First-principles results and model fittings are denoted by symbols and solid lines, respectively.

Figure 2

Model prediction (solid lines) and first-principles calculations (symbols) of $\mathcal{E}$ vs $P$ for $1S1B2C$ superlattice.

Figure 3

Dielectric response of $nSnBnC$ superlattice in (a) paraelectric and (b) ferroelectric regime.

Figure 4

Model interface dipole densities.