Band dispersion, photoemission satellites, and Fermi liquid behavior at T ⪢ TK in 5f heavy fermion systems

We present UV photoemission spectroscopy (UPS) data on the alloy system UPd3−xPtx. In the double hexagonal phase (x < 2.4), where the electrons are known to be localized, we obtain two gaussian 5f features in the photoemission spectrum (a peak just below EF and a satellite at≈−1.0 to −1.5 eV). This satellite structure carries over into the itinerant phase (x > 2.4) except that the low-binding energy features are now locked in at EF and show evidence for energy dispersion already at room temperature. This is consistent with well-defined bands. It would appear that Fermi liquid behavior already exists at room temperature. There is evidence for satellite formation even in well-behaved narrow band systems (USn3), so that apart from satellite intensity they are spectroscopically indistinguishable from heavy fermions.