Polarization and Dielectric Properties of BiFeO3-BaTiO3 Superlattice-Structured Ferroelectric Films.

Yuji Noguchi,Hiroki Matsuo

doi:10.3390/nano11071857

Abstract

Superlattice-structured epitaxial thin films composed of Mn(5%)-doped BiFeO3 and BaTiO3 with a total thickness of 600 perovskite (ABO3) unit cells were grown on single-crystal SrTiO3 substrates by pulsed laser deposition, and their polarization and dielectric properties were investigated. When the layers of Mn-BiFeO3 and BaTiO3 have over 25 ABO3 unit cells (N), the superlattice can be regarded as a simple series connection of their individual capacitors. The superlattices with an N of 5 or less behave as a unified ferroelectric, where the BaTiO3 and Mn-BiFeO3 layers are structurally and electronically coupled. Density functional theory calculations can explain the behavior of spontaneous polarization for the superlattices in this thin regime. We propose that a superlattice formation comprising two types of perovskite layers with different crystal symmetries opens a path to novel ferroelectrics that cannot be obtained in a solid solution system.

Highlights

Division of Information and Energy, Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1, Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
The experimental results for Mn-doped BiFeO3 films reveal that the crystal symmetry and the spontaneous polarization (Ps ) are not influenced by the doping of Mn up to 10%, and we considered BiFeO3 instead of Mn-doped BiFeO3 for simplicity
These results indicate that the monoclinic distortion, similar to the bulk, is maintained monoclinic symmetry appear, whereas those were not observed for an N of 5 (Figure S2d) forintegrated the superlattice with Nof

Summary

Introduction

Division of Information and Energy, Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1, Kurokami, Chuo-ku, Kumamoto 860-8555, Japan. International Research Organization for Advanced Science & Technology (IROAST), Kumamoto University, Abstract: Superlattice-structured epitaxial thin films composed of Mn(5%)-doped BiFeO3 and BaTiO3 with a total thickness of 600 perovskite (ABO3 ) unit cells were grown on single-crystal SrTiO3 substrates by pulsed laser deposition, and their polarization and dielectric properties were investigated. Pb(Zr, Ti)O3 , is representative, composed of ferroelectric PbTiO3 in tetragonal symmetry, and antiferroelectric PbZrO3 in rhombohedral symmetry [1,2]. In this system, the dielectric and piezoelectric properties are maximized near the compositiondriven phase boundary [2], called the morphotropic phase boundary (MPB) [3], between the tetragonal and rhombohedral structures.

Methods

Discussion

Conclusion