We have studied the electronic structure of CeNiSn, a valence-fluctuating Ce compound which opens a small gap at low temperatures, by photoemission spectroscopy in comparison with the Kondo systems CePdSn and CePtSn. The Sn 5p band crosses the Fermi level in every compound. The Ni 3d band is located close to the Fermi level and shown to be incompletely filled due to hybridization with the unoccupied Sn 5p states. The Ce core-level spectra indicate that CeNiSn is a valence-fluctuating compound very close to a trivalent system. The Ce 4f states are hybridized with the Ni 3d and Sn 5p band states; the Ce 4f–Sn 5p hybridization is suggested to be stronger than the Ce 4f–Ni 3d hybridization.

• Received 24 September 1992

DOI:https://doi.org/10.1103/PhysRevB.47.1754