Nanoscale domains in strained epitaxial BiFeO3 thin Films on LaSrAlO4 Substrate

TL;DR

This study investigates the nanoscale domain structures in strained BiFeO3 thin films grown on LaSrAlO4 substrates, revealing coexisting phases and stripe domains due to large misfit strains, using advanced diffraction and microscopy techniques.

Contribution

It demonstrates the stabilization of tetragonal-like and rhombohedral-like phases and their nanoscale domain patterns in strained BiFeO3 thin films, providing new insights into strain-induced phase coexistence.

Findings

Identification of tetragonal-like phase with c ~4.65 Å

Detection of rhombohedral-like phase at thickness ≥50 nm

Observation of nanoscale stripe domain structures

Abstract

BiFeO3 thin films with various thicknesses were grown epitaxially on (001) LaSrAlO4 single crystal substrates using pulsed laser deposition. High resolution x-ray diffraction measurements revealed that a tetragonal-like phase with c-lattice constant ~4.65 {\AA} is stabilized by a large misfit strain. Besides, a rhombohedral-like phase with c-lattice constant ~3.99 {\AA} was also detected at film thickness of ~50 nm and above to relieve large misfit strains. In-plane piezoelectric force microscopy studies showed clear signals and self-assembled nanoscale stripe domain structure for the tetragonal-like regions. These findings suggest a complex picture of nanoscale domain patterns in BiFeO3 thin films subjected to large compressive strains.