title: Pixelated detectors and improved efficiency for magnetic imaging in STEM differential phase contrast.
abstract: The application of differential phase contrast imaging to the study of polycrystalline magnetic thin films and nanostructures has been hampered by the strong diffraction contrast resulting from the granular structure of the materials. In this paper we demonstrate how a pixelated detector has been used to detect the bright field disk in aberration corrected scanning transmission electron microscopy (STEM) and subsequent processing of the acquired data allows efficient enhancement of the magnetic contrast in the resulting images. Initial results from a charged coupled device (CCD) camera demonstrate the highly efficient nature of this improvement over previous methods. Further hardware development with the use of a direct radiation detector, the Medipix3, also shows the possibilities where the reduction in collection time is more than an order of magnitude compared to the CCD. We show that this allows subpixel measurement of the beam deflection due to the magnetic induction. While the detection and processing is data intensive we have demonstrated highly efficient DPC imaging whereby pixel by pixel interpretation of the induction variation is realised with great potential for nanomagnetic imaging.
authors.affiliation: Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: Matus
authors.initials: M
authors.lastname: Krajnak
authors.affiliation: Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: Damien
authors.initials: D
authors.lastname: McGrouther
authors.affiliation: Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: Dzmitry
authors.initials: D
authors.lastname: Maneuski
authors.affiliation: Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: Val O'
authors.initials: VO
authors.lastname: Shea
authors.affiliation: Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom. Electronic address: stephen.mcvitie@glasgow.ac.uk.
authors.forename: Stephen
authors.initials: S
authors.lastname: McVitie
keywords: 4D electron microscopy; Differential phase contrast; Magnetic thin films; STEM