Universität Osnabrück, Graduiertenkolleg Mikrostruktur oxidischer

GRADUIERTENKOLLEG MIKROSTRUKTUR OXIDISCHER KRISTALLE 17
Fig 2. Comparison and measured XPS valence bands (thick solid line), the calculated total DOS (solid line) and
the convoluted DOS (with Lorentzians of half-width 0.4 eV and taking into account appropiate cross-sections
for partials bands with l-symmetry; dashed line) for LaNi5-xCu5
Fig. 3 The temperature dependence of the
magnetic susceptibilities for the LaNi5-xCux system
The experimentally determined nickel moments are smaller than the value characteristic for Ni 2+ ions, considering
only the spin contribution (2.83 µB/ion), and decrease with increasing Cu content. Two mechanism may be
considered. For the first, it is supposed that the values of average amplitude of the local spin fluctuations at T <
T * are not saturated even for LaNi5 and the saturation decreases as a result of diminution of the exchangeenhancement
factor when Ni is replaced by Cu. The second mechanism is considered a gradual hybridization of
the Ni 3d band with Cu states as a result of increasing the Cu content. In this case the electronic configuration of
Ni must be gradually modified. Only effects due to weak hybridization between Ni and Cu d states were evidenced
from the analysis of the XPS spectra as well as from the band-structure calculations. Thus, the smaller
effective nickel moment cannot be attributed to a gradual filling of the Ni 3d band. Finally, we concluded that