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Zusammenfassung:
Photoemission experiments performed at an incident photon energy of 70 eV provide a clear view of the transition-element-derived d bands in the systems CeT2Si2, with T=Cu,Ag,Au,andPd. Spectra taken at hν=122 eV display both a resonant 4f emission at 2-3 eV below EF, and a resonant emission near EF. The total intensity of the latter feature, which has been observed in other Ce-based systems and identified as having strong 4f character in γ-cerium and CeAl2, appears to track the intensities of the transition-element-derived d density of states near EF. In superconducting CeCu2Si2, the EF feature has its maximum at 0.25 eV, whereas we find it at significantly higher binding energies (∼0.6 eV) in the three magnetic systems (T=Ag,Au,andPd). This observation suggests markedly smaller electronic specific-heat (γ) values in the magnetic compounds as compared with γ≃1 J mole−1 K−2 generated by heavy fermions in CeCu2Si2.
