  Charge-order-driven ferroelectrics are an emerging class of functional
materials, distinct from conventional ferroelectrics, where electron-dominated
switching can occur at high frequency. Despite their promise, only a few
systems exhibiting this behavior have been experimentally realized thus far,
motivating the need for new materials. Here, we use density functional theory
to study the effect of artificial structuring on mixed-valence solid-solution
La$_{1/3}$Sr$_{2/3}$FeO$_{3}$ (LSFO), a system well-studied experimentally. Our
calculations show that A-site cation (111)-layered LSFO exhibits a
ferroelectric charge-ordered phase in which inversion symmetry is broken by
changing the registry of the charge order with respect to the superlattice
layering. The phase is energetically degenerate with a ground-state
centrosymmetric phase, and the computed switching polarization is 39
$\mu$C/cm$^{2}$, a significant value arising from electron transfer between Fe
ions. Our calculations reveal that artificial structuring of LSFO and other
mixed valence oxides with robust charge ordering in the solid solution phase
can lead to charge-order-induced ferroelectricity.
