Stacking-dependent electronic structure of ultrathin perovskite bilayers

TL;DR

This paper develops a first-principles theoretical framework to study the electronic structure of ultrathin perovskite bilayers, extending twistronics concepts beyond van der Waals materials.

Contribution

It introduces ab initio tight-binding and minimal effective models for perovskite bilayers, enabling detailed analysis of their electronic properties.

Findings

Constructed a first-principles tight-binding model for perovskite bilayers.

Developed a minimal 3-band effective model for valence bands.

Provided model parameters for Sr$_2$TiO$_4$, Ca$_2$TiO$_4$, and Ba$_2$TiO$_4$.

Abstract

Twistronics has received much attention as a new method to manipulate the properties of 2D van der Waals structures by introducing moir\'e patterns through a relative rotation between two layers. Here we begin a theoretical exploration of twistronics beyond the realm of van der Waals materials by developing a first-principles description of the electronic structure and interlayer interactions of ultrathin perovskite bilayers. We construct both an ab initio tight-binding model as well as a minimal 3-band effective model for the valence bands of monolayers and bilayers of oxides derived from the Ruddlesden-Popper phase of perovskites, which is amenable to thin-layer formation. We illustrate the approach with the specific example of Sr$_2$TiO$_4$ layers but also provide model parameters for Ca$_2$TiO$_4$ and Ba$_2$TiO$_4$ .