TY  - JOUR
AU  - Beleggia, M.
AU  - Kasama, T.
AU  - Larson, D. J.
AU  - Kelly, T. F.
AU  - Dunin-Borkowski, Rafal
AU  - Pozzi, G.
TI  - Towards quantitative off-axis electron holographic mapping of the electric field around the tip of a sharp biased metallic needle
JO  - Journal of applied physics
VL  - 116
IS  - 2
SN  - 1089-7550
CY  - Melville, NY
PB  - American Inst. of Physics
M1  - FZJ-2015-02599
SP  - 024305 
PY  - 2014
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000340267600060
DO  - DOI:10.1063/1.4887448
UR  - https://juser.fz-juelich.de/record/189432
ER  -