Large tensile strain induced monoclinic MB phase in BiFeO3 epitaxial thin films on PrScO3 substrate

TL;DR

This study reveals that tensile strain induces a monoclinic MB phase with large in-plane polarization in BiFeO3 thin films on PrScO3, highlighting the role of substrate distortion in domain structure formation.

Contribution

It demonstrates the emergence of a monoclinic MB phase in tensile-strained BiFeO3 films and links substrate distortion to domain formation, advancing understanding of strain effects in ferroelectric thin films.

Findings

MB phase observed in tensile-strained BiFeO3 films

Large in-plane polarization of 85 μC/cm² in MB phase

Substrate monoclinic distortion influences domain structure

Abstract

Crystal and domain structures of tensile-strained BiFeO3 films grown on orthorhombic (110)o PrScO3 substrates were investigated. All films possess a MB-type monoclinic structure with 109o stripe domains oriented along the [\=i10]o direction. For films thicknesses less than ~40 nm, presence of well-ordered domains is proved by the detection of satellite peaks in synchrotron x-ray diffraction studies. For thicker films, For thicker films, only the Bragg reflections from tilted domains were detected. This is attributed to the broader domain size distribution in thicker films.Using planar electrodes,the in-plane polarization of the MB phase is determined to be 85 uC/cm2, which is much larger than that of compressive strained BiFeO3 films. Our results further reveal that the substrate monoclinic distortion plays a major role in determining the stripe domain formation of the rhombohedral ferroic epitaxial thin films, which sheds light to the understanding of elastic domain structure evolution in many other functional oxide thin films as well.