A STUDY OF THE ELECTRONIC-STRUCTURE OF GDMN2 BY APPEARANCE-POTENTIAL SPECTROSCOPY (SXAPS)

The GdMn2 intermetallic has been studied using soft X-ray appearance potential spectroscopy (SXAPS) which exploits the abrupt changes in the total X-ray emission associated with the thresholds for the excitations of core levels of the atoms in the surface region of the materials. This technique is highly sensitive to the density of states at the Fermi level and is therefore particularly suitable for investigating the changes in the unoccupied density of states as a result of alloying rare earths with transition metals. The SXAPS spectra of the M(4,5) levels of Gd and the L(2,3) levels of Mn in the intermetallic are compared with the corresponding elemental spectra. These core levels exhibit a positive chemical shift. The experimentally observed core level shift is a sum of the shifts resulting from charge transfer and hybridization. The charge transfer shift is approximated by the Fermi energy shift. The Fermi energies in the pure elements and in the intermetallic have been estimated from the free electron theory model. Utilizing these Fermi level and core level shifts, the hybridization effects between 3d and 5d bands are obtained in this intermetallic. The 3d-5d hybridization plays a significant role in the magnetism observed in the intermetallic.