Boundaries for efficient use of electron vortex beams to measure magnetic properties

TL;DR

This paper theoretically investigates the use of electron vortex beams for high-resolution magnetic property measurements, identifying conditions under which EVB provides meaningful magnetic information.

Contribution

It provides a theoretical framework and simulations that define the effective boundaries for using EVB in magnetic measurements at atomic resolution.

Findings

EVB wider than interatomic distance offers no advantage over ordinary beams.

Atomic resolution EVB can detect spin and orbital magnetic moments.

Boundaries for effective EVB magnetic measurements are established.

Abstract

Development of experimental techniques for characterization of magnetic properties at high spatial resolution is essential for progress in miniaturization of magnetic devices, for example, in data storage media. Inelastic scattering of electron vortex beams (EVB) was recently reported to contain atom-specific magnetic information. We have developed a theoretical description of inelastic scattering of EVB on crystals and performed simulations for EVB of different diameters. We show that use of an EVB wider than an interatomic distance does not provide any advantage over an ordinary convergent beam without angular momentum. On the other hand, in the atomic resolution limit, electron energy loss spectra measured by EVB are strongly sensitive to the spin and orbital magnetic moments of studied matter, when channeling through or very close to the atomic columns. Our results demonstrate the boundaries for efficient use of EVB in measurement of magnetic properties.