XMCD at the L_II,III edges of Er in ErMn₂, ErFe ₂, ErCo₂, ErNi₂, and ErAl₂ laves phases and in Er₂(SO₄)₃, 8H₂0

X-ray magnetic circular dichroism (XMCD) measurements have been performed at the L_II,III edges of Er in the intermetallic compounds ErMn ₂, ErFe₂, ErCo₂, ErNi₂, and ErAl₂, as well as in the ionic compound Er₂(SO ₄)₃,8H₂0, in order to study the evolution of the XMCD spectra as a function of the 5d states filling and/or their hybridization with magnetic or nonmagnetic electronic states. Almost all the spectra present the same general features, confirming that the 4f-5d intra-atomic coupling is a key point to explain XMCD spectra. Thus, we analyze the models based on this interaction, proposed to account for the unexpected sign of E1 -XMCD measurements, as well as the nonstatistical branching ratio between XMCD at the L_II and L_III edges. We underline the impossibilities of reproducing our measurements using these models. Moreover, we point out the special role played by Fe which leads, at the L_II edge of Er, to a significant modification of the shape of XMCD spectrum and an unexpected temperature dependence. The XMCD revealed an unexpected behavior of the 5d magnetic polarization in these compounds which is not visible in macroscopic measurements. This also demonstrates the non-negligible role played by the 5d-3d hybridization.