VALENCE-BAND PHOTOEMISSION-STUDY OF SINGLE-CRYSTALLINE CENISN

The electronic structure of single crystalline CeNiSn has been investi gated using photoemission spectroscopy. The extracted Ce 4f spectrum e xhibits three peak structures; the typical Fermi level and 2 eV peaks, and another between them, similar to 0.9 eV below the Fermi level E-F . The near-E-F peak reflects a substantial Ce 4f-Sn sp hybridization, whereas the 0.9 eV peak arises from the Ce 4f-Ni 3d and Ce 5d-Ni 3d hy bridization. A Ni 3d satellite feature is observed about 6 eV below th e Ni 3d main band, indicating a strong Ni 3d Coulomb correlation in Ce NiSn. The high-resolution photoemission study indicates a finite metal lic density of states at EF implying a semimetallic ground state. The electronic states near EF are found to have mixed character from the S n sp, Ce 5d, Ce 4f, and Ni 3d electrons. Constant-initial-state and co nstant-final-state yield spectra across the 4d-->4f threshold indicate the Ce valence to be close to 3+.