Theory of hypothetical ferroelectric superlattices incorporating head-to-head and tail-to-tail 180$^\circ$ domain walls

TL;DR

This paper proposes a theoretical method to stabilize head-to-head and tail-to-tail ferroelectric domain walls in superlattices through atomic layer substitution, confirmed by first-principles calculations.

Contribution

It introduces a novel approach to stabilize otherwise incompatible domain walls in ferroelectrics using atomic layer substitution, supported by predictive first-principles modeling.

Findings

Stable HH and TT domain walls achieved in superlattices with atomic substitutions.

Alternating polarization confirmed in the superlattice structure.

Presence of transverse polarization component in the domain structure.

Abstract

While electrical compatibility constraints normally prevent head-to-head (HH) and tail-to-tail (TT) domain walls from forming in ferroelectric materials, we propose that such domain walls could be stabilized by intentional growth of atomic layers in which the cations are substituted from a neighboring column of the periodic table. In particular, we carry out predictive first-principles calculations of superlattices in which Sc, Nb, or other substitutional layers are inserted periodically into PbTiO$_3$. We confirm that this gives rise to a domain structure with the longitudinal component of the polarization alternating from domain to domain, and with the substitutional layers serving as HH and TT domain walls. We also find that a substantial transverse component of the polarization can also be present.