Role of symmetry in quantitative EMCD experiments

TL;DR

This paper analyzes various experimental geometries in EMCD measurements, highlighting the importance of symmetry considerations and simulations to accurately interpret the dichroic signals.

Contribution

It provides a detailed analysis of asymmetries in EMCD setups and emphasizes the advantages of three-beam geometry and the necessity of simulations.

Findings

Asymmetries significantly affect EMCD signals.

Three-beam geometry offers advantages over other setups.

Simulations are crucial for accurate EMCD analysis.

Abstract

We have analysed a number of experimental geometries (two and three-beam geometry, general systematic row setup, zone axis orientation) for the electron magnetic circular dichroism measurements (EMCD). The effect of asymmetries in those setups is described in detail, explaining the advantages of the three-beam geometry. We observe a complicated thickness and orientation dependence of the dichroic signal and asymmetries. Therefore we stress the importance of the simulations, which should accompany the EMCD experiments.