Low Symmetry Phase in (001) BiFeO$_3$ Epitaxial Constrained Thin Films

TL;DR

This study reveals that (001) BiFeO3 epitaxial thin films exhibit a low-symmetry monoclinic phase at room temperature, differing from the rhombohedral phase seen in bulk crystals, using synchrotron x-ray diffraction.

Contribution

It demonstrates the existence of a low-symmetry monoclinic phase in (001) BiFeO3 thin films, highlighting a phase stability change due to epitaxial constraints.

Findings

Identification of low-symmetry phase using synchrotron x-ray diffraction.

Transition from rhombohedral to monoclinic structure in thin films.

Room temperature phase stability change due to epitaxial strain.

Abstract

The lattice of (001)-oriented BiFeO$_3$ epitaxial thin film has been identified by synchrotron x-ray diffraction. By choosing proper scattering zones containing the fixed (001) reflection, we have shown that low-symmetry phases similar to a $M_A$ phase exist in the thin film at room temperature. These results demonstrate a change in phase stability from rhombohedral in bulk single crystals, to a modified monoclinic structure in epitaxial thin films.