Evidence of rhombohedral structure within BiFeO3thin film grown on SrTiO3

Comprehensive crystal structure analysis was performed for a BiFeO3thin layer (?30 nm) grown on a SrTiO3substrate using cross-sectional transmission electron microscopy along three different zone axes. Nano-beam electron diffraction patterns combined with structure factor calculations and high-resolution transmission electron microscopy images unambiguously revealed that the BiFeO3thin layer grew with a rhombohedral structure identical to its bulk form. No evidence of monoclinic and/or tetragonal distortion was found. The rhombohedral BiFeO3thin layer was found to grow onto SrTiO3by maintaining an epitaxial relationship in a manner minimizing the lattice mismatch at the BiFeO3/SrTiO3interface.