Electronic structure of the valence band of GdSx and Gd3S4

Electronic structure of clean surfaces of single crystals of magnetic compounds of sulfides of gadolinium GdSx (x = 0.8−1.25) with NaCl and Th3P4 structures has been investigated by ultra-violet and X-ray photoelectron, Auger and electron energy loss spectroscopy. Clean surfaces of GdSx were obtained by cleavage in situ in ultra-high vacuum and by ion bombardment followed by annealing in vacuum. Photoelectron spectra of the valence band of GdSx family have the similar structure with a maxima at 9 eV and 5 eV related to a photoemission from the 4f-states and valence band formed by 3p-states of S anions respectively and features in the region 0–2 eV associated with 6s-5d conduction band of GdSx. An analysis of electron energy loss spectra has shown that the main features in loss spectra at high beam energy are associated with the 4d-4f giant resonance, 5p-5d resonance and plasmon excitation. At low incident energy a prominent multiplet structure is observed and interpreted in terms of the dipole-forbidden 4f → 4f electron transitions.