The emerging technique EMCD, Energy-Loss Magnetic Chiral Dichoism, aims to measure the element-specific magnetic moment of solids at a nanometer scale using electron energy-loss spectroscopy in a transmission electron microscope (TEM) [1-3]. The magnetic moment information is carried in the electron energy-loss spectra obtained from two specific positions of particular electron diffraction patterns. In the last few years, EMCD has been extensively applied to probe 3d moments in 3d transition metal. Our work explores its application to both 4f moment and 3d moment by investigating Dy-M4,5 edges and Fe-L2,3 edges respectively in DyFe2/YFe2 superlattice.
As illustrated in figure 1, DyFe2 and YFe2 layers appear alternatively to form a superlattice with a specific bilayer repeat distance. Both DyFe2 and YFe2 crystalize in the same structure, making the superlattice actually a single crystal. For EMCD experimental setup, a specific three-beam condition has been settled in the TEM to detect the signals of Fe-L2,3 edges and Dy-M4,5 edges in the same condition. Spectra and dichroic signals are shown in figure 2. The influence of the dynamic diffraction effect on the Fe-L3 and Dy-M5 EMCD signal amplitudes is precisely analyzed, and it will be shown in this presentation that the opposite sign of these two peaks unambiguously proves the antiparallel alignment of net Fe 3d and Dy 4f moments. In addition, EMCD sum rules specified for M4,5 edges have been derived and their application conditions to Dy-M4,5 edges will be discussed in detail.
This work evidences that the EMCD technique is an effective tool to probe 4f moment and to study magnetic moment coupling in magnetic materials.
. Schattschneider, P. et al. Nature 441, 486–488 (2006).
. Warot-Fonrose, B. et al. Ultramicroscopy 108, 393–398 (2008).
. Fu, X. et al. Phys. Rev. B, in Press, (2016)
Acknowledgement: This work is supported by the French national project EMMA (ANR12 BS10 013 01) and by the European Union under the Seventh Framework Program under a contract for an Integrated Infrastructure Initiative Reference 312483-ESTEEM2.
To cite this abstract:Xiaoxiao Fu, Bénédicte Warot-Fonrose, Karine Dumesnil, Rémi Arras, Virginie Serin; Magnetic coupling of 4f and 3d moments by EMCD: application to DyFe2-based superlattices. The 16th European Microscopy Congress, Lyon, France. https://emc-proceedings.com/abstract/magnetic-coupling-of-4f-and-3d-moments-by-emcd-application-to-dyfe2-based-superlattices/. Accessed: May 26, 2020
EMC Abstracts - https://emc-proceedings.com/abstract/magnetic-coupling-of-4f-and-3d-moments-by-emcd-application-to-dyfe2-based-superlattices/