X-ray magnetic circular dichroism at L edges of Er in laves phase compounds

X-ray magnetic circular dichroism (XMCD) of the Er L absorption-edges is studied in the Laves phase compound ErFe₂ in order to confirm the mechanism proposed: XMCD spectra are dominated by the electric dipole transition from the core 2p states to the magnetically polarized Er 5d states, which are caused by (i) the intra-atomic exchange interaction of 4f electrons, with the enhancement of the dipole matrix element, as well as by (ii) the hybridization with the spin-polarized Fe 3d states. In addition, (iii) the electric quadrupole transition contributes appreciably. We point out that one can observe a novel temperature effect on the XMCD spectrum of Er at L₂ edge, since it consists of the contributions (i), (ii) and (iii) having a comparable order of magnitude but different signs and temperature dependences. We discuss the resultant temperature dependence of the XMCD spectrum with that recently observed in ErFe₂.