ORIGIN OF THE METALLIC CONDUCTIVITY IN PDCOO2 WITH DELAFOSSITE STRUCTURE

Valence state, valence band structure and specific heat of metallic ox ide PdCoO2 with the delafossite structure, which has alternative layer s of Pd, Co and O ions with a formation of each triangular lattice, ar e first investigated using polycrystalline samples by means of photoel ectron spectroscopy and specific heat measurements. The lowest electri cal resistivity in PdCoO, among the whole conductive oxides is attribu table to a half-filled band formed by s-d hybrid orbitals originated f rom the monovalent Pd ions and coordinated oxygens. (C) 1998 Elsevier Science B.V. All rights reserved.