Strong magnetic x-ray dichroism in 2pabsorption spectra of 3dtransition-metal ions

Abstract

From atomic calculations in crystal-field symmetry we find a very strong circular and linear dichroism in the 2p x-ray absorption edges of magnetically ordered 3d transition-metal ions. The spectral shape changes drastically with the character of the ground state, which is determined by the presence of a crystal field, and the relative magnitudes of the exchange and 3d spin-orbit interaction. The difference in integrated intensity of the 2p absorption for left- and right-circular polarization provides a measure for the 3d spin-orbit coupling in spherical and crystal-field symmetry. The anisotropic branching ratio depends on the spin-orbit interaction and the Van Vleck contribution of the exchange interaction. The results of our calculations provide a basis for the study of magnetic x-ray dichroism on materials with localized 3d electrons.