title: On the origin of differential phase contrast at a locally charged and globally charge-compensated domain boundary in a polar-ordered material.
abstract: Differential phase contrast (DPC) imaging in the scanning transmission electron microscope is applied to the study of a charged antiphase domain boundary in doped bismuth ferrite. A clear differential signal is seen, which matches the expected direction of the electric field at the boundary. However, further study by scanned diffraction reveals that there is no measurable deflection of the primary diffraction disc and hence no significant free E-field in the material. Instead, the DPC signal arises from a modulation of the intensity profile within the primary diffraction disc in the vicinity of the boundary. Simulations are used to show that this modulation arises purely from the local change in crystallographic structure at the boundary and not from an electric field. This study highlights the care that is required when interpreting signals recorded from ferroelectric materials using both DPC imaging and other phase contrast techniques.
authors.affiliation: SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: MacLaren
authors.affiliation: SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: LiQiu
authors.initials: L
authors.lastname: Wang
authors.affiliation: SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Damien
authors.initials: D
authors.lastname: McGrouther
authors.affiliation: SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Craven
authors.affiliation: SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: McVitie
authors.affiliation: Institute of Energy and Climate Research: Fundamental Electrochemistry (IEK-9), Forschungszentrum Jülich, 52425 Jülich, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Schierholz
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
authors.forename: András
authors.initials: A
authors.lastname: Kovács
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany; Central Facility for Electron Microscopy, RWTH Aachen University, 52074 Aachen, Germany.
authors.forename: Juri
authors.initials: J
authors.lastname: Barthel
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
authors.forename: Rafal E
authors.initials: RE
authors.lastname: Dunin-Borkowski