Effect of the asymmetry of dynamical electron diffraction on intensity of acquired EMCD signals.

One of the most challenging issues when characterizing magnetic materials in the transmission electron microscope is to obtain quantitative magnetic parameters at the nanometer scale. However, the dynamical diffraction effects of electrons in the periodic crystal structures make the quantitative energy loss magnetic circular dichroism (EMCD) technique complicated through deviations closely related to diffraction geometry. Here, we quantitatively demonstrate the up-down asymmetry existing in three-beam geometry of EMCD experiments and discuss its impact on experimental measurements via the calculations of dynamical diffraction theory. Lastly, we make a comparison of the quantitative magnetic parameters with and without considering this effect based on the experimental data of spinel structure NiFe2O4.