Detection of electron magnetic circular dichroism signals under zone axial diffraction geometry

• The zone axial (ZA) diffraction geometry is presented for EMCD technique.
• The detailed calculations for EMCD signals under ZA case are conducted.
• The EMCD signals are obtained under the ZA case in the experiments.
• The effect of dynamical effect on EMCD signals under ZA case is discussed.
• Site-specific EMCD signals of Fe in Y3Fe5O12 are obtained by specific ZA conditions.

EMCD (electron magnetic circular dichroism) technique provides us a new opportunity to explore magnetic properties in the transmission electron microscope. However, specific diffraction geometry is the major limitation. Only the two-beam and three-beam case are demonstrated in the experiments until now. Here, we present the more general case of zone axial (ZA) diffraction geometry through which the EMCD signals can be detected even with the very strong sensitivity to dynamical diffraction conditions. Our detailed calculations and well-controlled diffraction conditions lead to experiments in agreement with theory. The effect of dynamical diffraction conditions on EMCD signals are discussed both in theory and experiments. Moreover, with the detailed analysis of dynamical diffraction effects, we experimentally obtain the separate EMCD signals for each crystallographic site in Y3Fe5O12, which is also applicable for other materials and cannot be achieved by site-specific EMCD and XMCD technique directly. Our work extends application of more general diffraction geometries and will further promote the development of EMCD technique.