Spectral evidence for the importance of single-site effects in heavy-fermion uranium materials.

The 5f spectral weights in the heavy-fermion alloy system U/sub x/Y/sub 1-//sub x/Al2 (x = 0.1,0.02) have been measured by resonant photoemission. The major features of the spectra of the dilute systems are identical to those for x = 1, showing that single-site effects dominate the large--energy-scale features of the spectrum even in the concentrated system.