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Title: Towards quantitative off-axis electron holographic mapping of the electric field around the tip of a sharp biased metallic needle

We apply off-axis electron holography and Lorentz microscopy in the transmission electron microscope to map the electric field generated by a sharp biased metallic tip. A combination of experimental data and modelling provides quantitative information about the potential and the field around the tip. Close to the tip apex, we measure a maximum field intensity of 82 MV/m, corresponding to a field k factor of 2.5, in excellent agreement with theory. In order to verify the validity of the measurements, we use the inferred charge density distribution in the tip region to generate simulated phase maps and Fresnel (out-of-focus) images for comparison with experimental measurements. While the overall agreement is excellent, the simulations also highlight the presence of an unexpected astigmatic contribution to the intensity in a highly defocused Fresnel image, which is thought to result from the geometry of the applied field.
Authors:
 [1] ;  [2] ;  [1] ; ;  [3] ;  [4] ;  [5]
  1. Center for Electron Nanoscopy, Technical University of Denmark, Kongens Lyngby (Denmark)
  2. (Germany)
  3. CAMECA Instruments, Inc., Madison, Wisconsin 53711 (United States)
  4. Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungzentrum Jülich, Jülich (Germany)
  5. Department of Physics and Astronomy, University of Bologna, Bologna (Italy)
Publication Date:
OSTI Identifier:
22308977
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 2; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CHARGE DENSITY; DISTRIBUTION; ELECTRIC FIELDS; HOLOGRAPHY; SIMULATION; TRANSMISSION ELECTRON MICROSCOPY