Generation of a spin-polarized electron beam by multipoles magnetic fields

TL;DR

This paper explores how transverse magnetic fields with topological charges can manipulate electron spins, enabling the creation of spin-polarized electron beams and potential applications in electron microscopy.

Contribution

It introduces a novel method using multipole magnetic fields to generate spin-polarized electron beams and analyzes their effectiveness through numerical simulations.

Findings

Spin--magnetic interaction causes nonuniform spin precession.

The geometrical phase depends on the field's topological charge.

Numerical analysis shows potential for improved electron microscopes.

Abstract

The propagation of an electron beam in the presence of transverse magnetic fields possessing integer topological charges is presented. The spin--magnetic interaction introduces a nonuniform spin precession of the electrons that gains a space-variant geometrical phase in the transverse plane proportional to the field's topological charge, whose handedness depends on the input electron's spin state. A combination of our proposed device with an electron orbital angular momentum sorter can be utilized as a spin-filter of electron beams in a mid-energy range. We examine these two different configurations of a partial spin-filter generator numerically. The results of these analysis could prove useful in the design of improved electron microscope.