Assessing the achievable quantification accuracy of magnetic moments in noisy electron magnetic chiral dichroism spectra using modeling

Abstract

Electron magnetic chiral dichroism (EMCD) technique enables quantitative measurements of spin and orbital moments at a sub-nanometer resolution in principle, while it is practically challenging at high resolutions due to noise problems. Our work proposed a mathematical model that can be used to synthesize EMCD spectra with controllable noise levels and settable true values of magnetic moments. Using the model, the achievable quantification accuracy at different noise levels has been systematically assessed. The assessment has revealed the chain noise effect in routine post-processing steps and provided essential experimental instructions to improve quantification precision and accuracy at given noise levels. The ineffectiveness of several denoising methods in improving accuracy and precision has also been verified. Our work may stimulate the development of noise-dependent post-processing algorithms applicable to EMCD and advance the technique application, especially in research with a high demand for accuracy, such as mapping interfacial magnetic structures in nanomaterials.