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

Abstract

We have explored the influence of deposition pressure and temperature on the growth of $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_3$ thin films by pulsed laser deposition onto (001)-oriented $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3$ substrates. Single-phase $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_3$ films are obtained in a region close to ${10}^{-2}\mathrm{mbar}$ and $580°\mathrm{C}$ . In nonoptimal conditions, x-ray diffraction reveals the presence of Fe oxides or of ${\mathrm{Bi}}_2{\mathrm{O}}_3$ . We address the influence of these parasitic phases on the magnetic and electrical properties of the films and show that films with ${\mathrm{Fe}}_2{\mathrm{O}}_3$ systematically exhibit a ferromagnetic behavior, while single-phase films have a low bulklike magnetic moment. Conductive-tip atomic force microscopy mappings also indicate that ${\mathrm{Bi}}_2{\mathrm{O}}_3$ conductive outgrowths create shortcuts through the $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_3$ films, thus preventing their practical use as ferroelectric elements in functional heterostructures.