Soft X-ray appearance-potential spectroscopy studies of DyFe2 and ErFe2 intermetallics

The soft X-ray appearance-potential spectra (SXAPS) of the M_4,5 levels of Dy and Er and the L_2,3 levels of Fe in pure metals and their intermetallics DyFe₂ and ErFe₂ have been obtained in the energy range of 700–1500 eV. SXAPS probes the binding energies of the core levels and the distribution of local unfilled conduction-band states. Both the constituents of DyFe₂ show negative shifts with respect to the pure metals while those of ErFe₂ show a negative shift for Er and a positive shift for Fe. The widths of the Dy and Er peaks increase and that of the Fe decreases on alloying. The results are interpreted in terms of the Fermi level changes and the charge transfer from the rare earth to Fe. The discrepancy in Fe chemical shifts has been correlated to the electronic specific heat capacity coefficient reported for these intermetallics.