Quantitative moment study and coupling of 4f rare earth and 3d metal by transmitted electrons

We report a simultaneous investigation of 3d and 4f magnetic moments by exploring the Fe−L2,3 and Dy−M4,5 electron energy-loss edges of a DyFe2/YFe2 superlattice using the energy-loss magnetic chiral dichroism (EMCD) technique. Specific EMCD sum rules for M4,5 edges were established and carefully applied to the dichroic signal at Dy−M4,5 edges, giving an orbital to the effective spin moment ratio of 5.1±1.8. With dynamic diffraction effects considered, the opposite signs of Fe−L3 and Dy−M5 dichroic peaks unambiguously indicate the antiparallel alignment of net Fe 3d and Dy 4f moments. The EMCD technique is shown to be an effective tool to locally characterize the 4f moment of rare earth elements and study 3d−4f moment coupling.