Orbital character of the conduction band of delafossite PdCoO2 studied by polarization-dependent soft x-ray absorption spectroscopy

Abstract

We present the x-ray absorption spectra that show the Co valence state and the orbital character of the conduction band of delafossite PdCoO2. The Co 2p x-ray absorption spectra of PdCoO2 and PtCoO2 show that the Co ions have the trivalent low-spin configuration. The polarization-dependent O 1s absorption spectra reveal that the unoccupied density of states (DOS) near the Fermi level consists mainly of the Pd 4d(3z2-r2) states. The experimental O 2p(z) partial DOS (PDOS) is extracted from the polarization-dependent O 1s spectra and is compared with the theoretical PDOS by the local-density approximation, showing a good agreement. These observations provide a consistent picture on the origin of the good conductivity of the delafossite oxides.