Structural and electronic properties of two-dimensional freestanding BaTiO3/SrTiO3 heterostructures

Fanhao Jia, Shaowen Xu, Guodong Zhao, Chao Liu, and Wei Ren
Phys. Rev. B 101, 144106 – Published 27 April 2020
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Abstract

The successful preparation of the freestanding perovskite materials down to the monolayer limit [Ji et al., Nature (London) 570, 87 (2019)] provided the opportunity to make the two-dimensional (2D) oxide and heterostructure, which could be significantly distinctive from the conventional oxide superlattices and other 2D van der Waals heterostructures. By stacking one unit-cell BaTiO3 (BTO) and one unit-cell SrTiO3 (STO) on top of each other, we constructed two isolated bilayers of the 2D heterostructure systems. From our density functional theory simulation, their ground states exhibit an in-plane ferroelectricity in both BTO layer and STO layer, while the antiferrodistortive mode of the STO layer is totally suppressed. These two systems show band gaps in the range of 2–2.5 eV (by using HSE06), which are smaller than their monolayer and bulk phases. The layer arrangement strongly influences their electronic properties. We reveal that they adopt the type-II electronic band alignment. The tensile biaxial strain can strongly promote the ferroelectricity and increase the band gaps of these systems. Our results will contribute to the further understanding of layered materials based on the transition metal oxide perovskites and developing relevant experimental devices.

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  • Received 5 December 2019
  • Revised 29 February 2020
  • Accepted 31 March 2020

DOI:https://doi.org/10.1103/PhysRevB.101.144106

©2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Fanhao Jia*, Shaowen Xu*, Guodong Zhao, Chao Liu, and Wei Ren

  • Physics Department, Shanghai Key Laboratory of High Temperature Superconductors, State Key Laboratory of Advanced Special Steel, International Centre of Quantum and Molecular Structures, Shanghai University, Shanghai 200444, China

  • *These authors contributed equally to this work.
  • renwei@shu.edu.cn

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Issue

Vol. 101, Iss. 14 — 1 April 2020

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