Influence of parasitic phases on the properties of BiFeO3 epitaxial thin films

TL;DR

This study investigates how parasitic phases like Fe oxides and Bi2O3 affect the magnetic and electrical properties of BiFeO3 thin films grown by pulsed laser deposition, highlighting challenges for their use in ferroelectric devices.

Contribution

It demonstrates the impact of parasitic phases on BiFeO3 film properties and their formation conditions, providing insights for optimizing film quality for functional applications.

Findings

Fe2O3 phases induce ferromagnetism in films

Bi2O3 outgrowths create electrical shortcuts

Optimal growth conditions yield single-phase BiFeO3

Abstract

We have explored the influence of deposition pressure and temperature on the growth of BiFeO3 thin films by pulsed laser deposition onto (001)-oriented SrTiO3 substrates. Single-phase BiFeO3 films are obtained in a region close to 10-2 mbar and 580C. In non-optimal conditions, X-ray diffraction reveals the presence of Fe oxides or of Bi2O3. We address the influence of these parasitic phases on the magnetic and electrical properties of the films and show that films with Fe2O3 systematically exhibit a ferromagnetic behaviour, while single-phase films have a low bulk-like magnetic moment. Conductive-tip atomic force microscopy mappings also indicate that Bi2O3 conductive outgrowths create shortcuts through the BiFeO3 films, thus preventing their practical use as ferroelectric elements in functional heterostructures.