Achieving atomic resolution magnetic dichroism by controlling the phase symmetry of an electron probe

TL;DR

This paper demonstrates that by controlling the phase symmetry of an electron probe in a scanning transmission electron microscope, atomic resolution magnetic dichroism measurements can be achieved, broadening the scope beyond orbital angular momentum beams.

Contribution

It introduces a method to obtain atomic resolution EMCD signals through phase symmetry control, expanding the types of electron beams usable for magnetic measurements.

Findings

EMCD signals can be enhanced by phase symmetry control.

Phase distribution depends on magnetic symmetry and crystal structure.

The method achieves signal strength comparable to nanodiffraction techniques.

Abstract

The calculations presented here reveal that an electron probe carrying orbital angular momentum is just a particular case of a wider class of electron beams that can be used to measure electron magnetic circular dichroism (EMCD) with atomic resolution. It is possible to obtain an EMCD signal with atomic resolution by simply breaking the symmetry of the electron probe phase distribution using the aberration-corrected optics of an scanning transmission electron microscope. The required phase distribution of the probe depends on the magnetic symmetry and crystal structure of the sample. The calculations indicate that EMCD signals utilizing the phase of the electron probe are as strong as those obtained by nanodiffraction methods.