Generation of electron vortices using non-exact electric fields

TL;DR

This paper demonstrates how structured electric fields, specifically non-exact fields, can generate electron vortex beams, offering a versatile method for producing and manipulating electron vortices with various topological charges.

Contribution

It introduces a novel approach to generate electron vortex beams using non-exact electric fields and a specially designed device for versatile vortex creation.

Findings

Non-exact electric fields can produce electron vortices.

A device was fabricated to generate various vortex topological charges.

The method allows sequential and adjustable vortex generation.

Abstract

Vortices in electron beams can manifest several types of topological phenomena, such as the formation of exotic structures or interactions with topologically structured electromagnetic fields. For instance, the wavefunction of an electron beam can acquire a phase vortex upon propagating through a magnetic monopole, which, in practice, provides a convenient method for generating electron vortex beams. Here, we show how an electric field must be structured in order to achieve a similar effect. We find that, much as in the case of magnetic fields, closed but not exact electric fields can produce electron vortex beams. We proceed by fabricating a versatile near-obstruction-free device that is designed to approximately produce such fields and we systematically study their influence on incoming electron beams. With such a single device, electron vortex beams that are defined by a wide range of topological charges can be produced by means of a slight variation of an applied voltage. For this reason, this device is expected to be important in applications that rely on the sequential generation and manipulation of different types of electron vortices.