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arXiv · 1412.3517

Holographic generation of highly twisted electron beams

Vincenzo Grillo·Gian Carlo Gazzadi·Erfan Mafakheri·Stefano Frabboni·Ebrahim Karimi·Robert W. Boyd
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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.

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Vincenzo Grillo, Gian Carlo Gazzadi, Erfan Mafakheri, Stefano Frabboni, Ebrahim Karimi, Robert W. Boyd. 2014-12-11. Holographic generation of highly twisted electron beams. https://doi.org/10.1103/physrevlett.114.034801

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