High-resolution photoemission and x-ray absorption study of quasi-one-dimensional DCNQI-Cu salt

Abstract

We have made a high-resolution photoemission (PES) and x-ray absorption (XAS) study of quasi-one-dimensional partially deuterated (DMe-DCNQI) 2 Cu. The PES spectra in the metallic phase exhibit a power-law dependence on the electron binding energy ω on a high energy scale (~0.3 eV>|ω|>~0.05 eV) or at high temperatures (T>~300 K) while a weak but finite intensity is found at the Fermi level at low temperatures, indicating a weak 3D character. From the N 1 s and Cu 2 p XAS spectra, we clearly observe the mixed valence state of Cu and the strong anisotropy of the electronic structure although 3D character is also found.