TY  - JOUR
AU  - Pozzi, Giulio
AU  - Lu, Peng-Han
AU  - Tavabi, Amir H.
AU  - Duchamp, Martial
AU  - Dunin-Borkowski, Rafal
TI  - Generation of electron vortex beams using line charges via the electrostatic Aharonov-Bohm effect
JO  - Ultramicroscopy
VL  - 181
SN  - 0304-3991
CY  - Amsterdam
PB  - Elsevier Science
M1  - FZJ-2017-04051
SP  - 191–196
PY  - 2017
AB  - It has recently been shown that an electron vortex beam can be generated by the magnetic field surrounding the tip of a dipole-like magnet. This approach can be described using the magnetic Aharonov-Bohm effect and is associated with the fact that the end of a long magnetic rod can be treated approximately as a magnetic monopole. However, it is difficult to vary the magnetisation of the rod in such a setup and the electron beam vorticity is fixed for a given tip shape. Here, we show how a similar behaviour, which has the advantage of easy tuneability, can be achieved by making use of the electrostatic Aharonov-Bohm effect associated with an electrostatic dipole line. We highlight the analogies between the magnetic and electrostatic cases and use simulations of in-focus, Fresnel and Fraunhofer images to show that a device based on two parallel, oppositely charged lines that each have a constant charge density can be used to generate a tuneable electron vortex beam. We assess the effect of using a dipole line that has a finite length and show that if the charge densities on the two lines are different then an additional biprism-like effect is superimposed on the electron-optical phase.
LB  - PUB:(DE-HGF)16
C6  - pmid:28609665
UR  - <Go to ISI:>//WOS:000411170800023
DO  - DOI:10.1016/j.ultramic.2017.06.001
UR  - https://juser.fz-juelich.de/record/830517
ER  -