Photoemission study of the uranium ternary compounds U3T3X4 (T = Ni, Cu; X = Sn, Sb)

Valence-band structures of U3Ni3Sn4, U3Ni3Sb4, U3Cu3Sn4 and U3Cu3Sb4 ranging from a semiconductor to a heavy fermion system, are studied using photemission spectroscopy with synchrotron radiation. We found that the Ni 3d band in U3Ni3Sn4 is not fully filled up, the Cu 3d states in the ferromagnet U3Cu3Sb4 are strongly hybridized with the Sb 5p states, but the 3d states localized in the heavy-fermion compound U3Cu3Sn4. However, the U 5f emission spectra obtained by the resonant photoemission technique are nearly identical for all compounds and have an asymmetric peak of 1.6 eV in width. (author)