X-RAY PHOTOEMISSION SPECTROSCOPIC STUDY ON THE ELECTRONIC STATES IN THE MIXED SYSTEM BETWEEN CHARGE-TRANSFER AND MOTT-HUBBARD TYPE METALS -CO0.91S AND V0.91S

In order to study the change of the electronic states from the charge- transfer(CT) type metal to the Mott-Hubbard(MH) one, X-ray, photoemiss ion spectra are measured on the NiAs-type (Co1-xVx)(0.91)S (x less tha n or equal to 0.50) and V0.91S The asymmetry parameter alpha for S 2s and 2p core level spectra decrease with increasing x. This result indi cates that the local density of states of S atoms at the Fermi level d ecreases as a: increases; the system changes from the CT-type metal to the NH-one with x. The change in V 2p line shape with x suggests the possibility of the considerable hybridization between V 3d and S 3p in (Co1-xVx)(0.91)S at lower x region. This feature would be related to the appearance of the extra peak at binding energy E(B) = 2-3 eV in th e valence hand X-ray photoemission spectra.