Thickness dependence of SmNiO3 polar displacement uniformity

Determine whether the polar displacements (ionic off‑centering) in the SmNiO3 electrode of SmNiO3/BaTiO3 superlattices with SmNiO3 octahedral rotations disabled remain uniform across the SmNiO3 slab as the SmNiO3 thickness increases, and characterize any thickness-dependent evolution of the displacement profile.

Background

In the simplified SmNiO3/BaTiO3 superlattices studied with the octahedral rotations of SmNiO3 disabled, the authors observe that the polar displacements within the metallic SmNiO3 electrode are uniform across the entire SmNiO3 slab at the thicknesses considered. This behavior contrasts with prior observations in BaTiO3/SrRuO3 superlattices where polar displacements were confined to 2–3 unit cells near the interface.

The uniformity of SmNiO3 polar displacements has direct implications for how the polar discontinuity is screened and thus affects the stability of ferroelectric polarization in BaTiO3. Establishing how these displacements vary as the SmNiO3 electrode becomes thicker would clarify the screening mechanisms and the resulting interface charge compensation in such superlattices.