EVOLUTION OF THE SPECTRAL-FUNCTION IN MOTT-HUBBARD SYSTEMS WITH D(1) CONFIGURATION

We have studied the photoemission spectra of perovskite-type Ti3+ and V4+ oxides, which have formally the d1 configuration ranging from a Mott insulator to a paramagnetic metal. The results indicate that as the Mott-Hubbard gap closes, spectral weight is transferred from the upper and lower Hubbard bands to the region near the Fermi level with decreasing U/W (U, d-d Coulomb repulsion energy; W, one-electron d-band width), i.e., from the incoherent to the coherent part of the single-particle spectral function.