Holographic generation of highly twisted electron beams

TL;DR

This paper presents a method to generate highly twisted electron beams with orbital angular momentum up to 200ħ using nano-fabricated phase holograms, enabling new applications in material science and nanoparticle manipulation.

Contribution

The authors develop and demonstrate a novel holographic technique to produce electron beams with unprecedented high orbital angular momentum.

Findings

Successfully generated electron beams with up to 200ħ orbital angular momentum

Measured and validated the angular momentum values against simulations

Potential applications in studying magnetic properties and manipulating nanoparticles

Abstract

Free electrons can possess an intrinsic orbital angular momentum, similar to those in an electron cloud, upon free-space propagation. The wavefront corresponding to the electron's wavefunction forms a helical structure with a number of twists given by the \emph{angular speed}. Beams with a high number of twists are of particular interest because they carry a high magnetic moment about the propagation axis. Among several different techniques, electron holography seems to be a promising approach to shape a \emph{conventional} electron beam into a helical form with large values of angular momentum. Here, we propose and manufacture a nano-fabricated phase hologram for generating a beam of this kind with an orbital angular momentum up to 200$\hbar$. Based on a novel technique the value of orbital angular momentum of the generated beam are measured, then compared with simulations. Our work, apart from the technological achievements, may lead to a way of generating electron beams with a high quanta of magnetic moment along the propagation direction, and thus may be used in the study of the magnetic properties of materials and for manipulating nano-particles.