title: Strain Localization in Thin Films of Bi(Fe,Mn)O3 Due to the Formation of Stepped Mn(4+)-Rich Antiphase Boundaries.
abstract: The atomic structure and chemistry of thin films of Bi(Fe,Mn)O3 (BFMO) films with a target composition of Bi2FeMnO6 on SrTiO3 are studied using scanning transmission electron microscopy imaging and electron energy loss spectroscopy. It is shown that Mn(4+)-rich antiphase boundaries are locally nucleated right at the film substrate and then form stepped structures that are approximately pyramidal in three dimensions. These have the effect of confining the material below the pyramids in a highly strained state with an out-of-plane lattice parameter close to 4.1 Å. Outside the area enclosed by the antiphase boundaries, the out-of-plane lattice parameter is much closer to bulk values for BFMO. This suggests that to improve the crystallographic perfection of the films whilst retaining the strain state through as much of the film as possible, ways need to be found to prevent nucleation of the antiphase boundaries. Since the antiphase boundaries seem to form from the interaction of Mn with the Ti in the substrate, one route to perform this would be to grow a thin buffer layer of pure BiFeO3 on the SrTiO3 substrate to minimise any Mn-Ti interactions.
authors.affiliation: SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK. ian.maclaren@glasgow.ac.uk.
authors.forename: I
authors.initials: I
authors.lastname: MacLaren
authors.affiliation: SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK.
authors.forename: B
authors.initials: B
authors.lastname: Sala
authors.affiliation: SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK.
authors.forename: S M L
authors.initials: SM
authors.lastname: Andersson
authors.affiliation: SuperSTEM Laboratory, STFC Daresbury Laboratories, Keckwick Lane, Warrington, WA4 4AD, UK.|Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK.|Present Address: Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090, Vienna, Austria.
authors.forename: T J
authors.initials: TJ
authors.lastname: Pennycook
authors.affiliation: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.|State Key Lab of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, NO.4, Section 2, North Jianshe Road, Chengdu, 610054, China.
authors.forename: J
authors.initials: J
authors.lastname: Xiong
authors.affiliation: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
authors.forename: Q X
authors.initials: QX
authors.lastname: Jia
authors.affiliation: Department of Materials Science, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK.
authors.forename: E-M
authors.initials: EM
authors.lastname: Choi
authors.affiliation: Department of Materials Science, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK.
authors.forename: J L
authors.initials: JL
authors.lastname: MacManus-Driscoll
keywords: Antiphase boundaries; Bismuth ferrite; Multiferroic; Scanning transmission electron microscopy (STEM); Strain; Thin films