Eur. Phys. J. B 26, 449-453 (2002)
https://doi.org/10.1140/epjb/e20020113

The electronic structure of the doped one-dimensional transition metal oxide Y_2-xCa_xBaNiO₅ studied using X-ray absorption

¹ Institute for Solid State Research, IFW Dresden, 01171 Dresden, Germany
² Department of Inorganic Chemistry, University of Utrecht Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands
³ Correlated Electron Research Center, AIST, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan
⁴ Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany

Corresponding author: ^a m.knupfer@ifw-dresden.de

Received: 7 January 2002
Published online: 15 April 2002

Abstract

A strong anisotropic distribution of the holes in Ni 3d and O 2p orbitals is observed in the polarization dependent O 1s and Ni X-ray absorption spectroscopy of the linear-chain nickelate Y_2-xCa_xBaNiO₅ (x = 0, 0.05, 0.1, 0.2), which demonstrates the one-dimensional nature of the electronic state in these compounds. The holes introduced by Ca-doping occupy both O 2p and Ni 3d orbitals along the NiO₅ chains. By comparing the experimental Ni absorption spectra of Y_2-xCa_xBaNiO₅ to those from charge transfer multiplet calculations we can derive the orbital character of the additional holes to be of ~60% O2p and ~40% Ni 3d.