Magnetic circular X-ray dichroism at the rare-earth L_2,3 edges

We report a successful interpretation of the systematic trend observed in the magnetic circular X-ray dichroism at the rare-earth L_2,3 edges, taking into account the novel role played by the 4f-5d intra-atomic exchange interaction, the contraction of the radial part of the 5d wave function which results in the enhancement of the 2p-5d electric dipole matrix-element, and the usual role of the polarization of the 5d ground state. In addition, a contribution of the quadrupole transition just below the edges is discussed.