Spin-to-Orbital Angular Momentum Conversion and Spin-Polarization Filtering in Electron Beams

TL;DR

This paper introduces a novel space-variant Wien filter that converts electron spin angular momentum into orbital angular momentum, enabling generation of vortex beams and effective spin-polarization filtering, with potential applications to neutrons and atoms.

Contribution

It presents a new device design that manipulates spin and orbital angular momentum through geometrical phase, expanding capabilities in electron beam control.

Findings

Can generate electron vortex beams with orbital angular momentum.

Acts as an effective spin-polarization filter for unpolarized beams.

Applicable to neutron and atom beams as well.

Abstract

We propose the design of a space-variant Wien filter for electron beams that induces a spin half-turn and converts the corresponding spin angular momentum variation into orbital angular momentum of the beam itself by exploiting a geometrical phase arising in the spin manipulation. When applied to a spatially coherent input spin-polarized electron beam, such a device can generate an electron vortex beam, carrying orbital angular momentum. When applied to an unpolarized input beam, the proposed device, in combination with a suitable diffraction element, can act as a very effective spin-polarization filter. The same approach can also be applied to neutron or atom beams.