%0 Journal Article
%A Pozzi, Giulio
%A Lu, Peng-Han
%A Tavabi, Amir H.
%A Duchamp, Martial
%A Dunin-Borkowski, Rafal
%T Generation of electron vortex beams using line charges via the electrostatic Aharonov-Bohm effect
%J Ultramicroscopy
%V 181
%@ 0304-3991
%C Amsterdam
%I Elsevier Science
%M FZJ-2017-04051
%P 191–196
%D 2017
%X 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.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:28609665
%U <Go to ISI:>//WOS:000411170800023
%R 10.1016/j.ultramic.2017.06.001
%U https://juser.fz-juelich.de/record/830517