L. Duo et al., EMPTY AND FILLED VALENCE-ELECTRON STATES OF LU TRANSITION-METAL COMPOUNDS - AN UV SPECTROSCOPY STUDY, Physical review. B, Condensed matter, 49(15), 1994, pp. 10159-10165
Ajoint uv-photoemission (hnu=21.2 and 40.8 eV) and inverse-photoemissi
on (hnu=11-17 eV) spectroscopy investigation is reported on Lu and som
e Lu-transition-metal (M compounds, namely LuCo2, LuRh2, and Lu7Rh3 fo
cused on the Lu and the M d-derived filled and empty electron states.
The analysis is performed by considering the substitution effects of a
3d with a 4d M partner (LuCo2 VS LuRh2) and by changing the stoichiom
etry and structure within the Lu-Rh phase diagram (LuRh2 VS Lu7Rh3 vs
pure Lu). In LuRh2 the electron states, both below and above the Fermi
level (E(F)), appear at lower energy (i.e., more bounded) as compared
to LuCo2. Lu7Rh3 shows a strong narrowing of the Rh d band below E(F)
, due to a strongly decreased Rh-Rh interaction whereas above E(F) a s
imilarity with pure Lu at high-electron energies and a significant red
istribution of the Rh 4d states are observed. A critical discussion of
the results considering (i) the crystal structures and the atomic coo
rdinations, and (ii) thermochemical estimations is performed. A compar
ison of the LuCo2 data with published theoretical results indicates th
at the d-derived empty electron states are appropriately described wit
hin a single-particle picture at variance with the d occupied states f
or which remarkable discrepancies between theory and experiment are fo
und probably due to the larger radial extent and more pronounced deloc
alization of the antibonding empty states with respect to the filled s
tates. Some general consequences of these effects will be discussed.