The need to acquire multiple angle-resolved electron energy loss spectra (EELS) is one of the several critical challenges associated with electron magnetic circular dichroism (EMCD) experiments. If the experiments are performed by scanning a nanometer to atomic-sized electron probe on a specific region of a sample, the precision of the local magnetic information extracted from such data highly depends on the accuracy of the spatial registration between multiple scans. For an EMCD experiment in a 3-beam orientation, this means that the same specimen area must be scanned four times while keeping all the experimental conditions same. This is a non-trivial task as there is a high chance of morphological and chemical modification as well as non-systematic local orientation variations of the crystal between the different scans due to beam damage, contamination and spatial drift. In this work, we employ a custom-made quadruple aperture to acquire the four EELS spectra needed for the EMCD analysis in a single electron beam scan, thus removing the above-mentioned complexities. We demonstrate a quantitative EMCD result for a beam convergence angle corresponding to sub-nm probe size and compare the EMCD results for different detector geometries.
@article{arxiv.2211.09087,
title = {Single scan STEM-EMCD in 3-beam orientation using a quadruple aperture},
author = {Hasan Ali and Sharath Kumar Manjeshwar Sathyanath and Cheuk-Wai Tai and Jan Rusz and Toni Uusimaki and Björgvin Hjörvarsson and Thomas Thersleff and Klaus Leifer},
journal= {arXiv preprint arXiv:2211.09087},
year = {2022}
}