Abstract
The electronic structure of and for various values of has been investigated using hard x-ray photoemission spectroscopy. The experimental results establish that the cleaving of compounds occurs predominantly in the complex, leading to charged surfaces at higher and to uncharged surfaces at lower values. The bulk component of the core-level spectra exhibits a shift in binding energy as a function of , from which a shift of the chemical potential as a function of hole concentration in the layers could be derived. The doping dependence of the chemical potential across the transition from a Mott-Hubbard insulator to a Fermi-liquid-like metal is very different in these two series of compounds. In agreement with previous studies in the literature the chemical-potential shift in is close to zero for small hole concentrations. In , similar to all other doped cuprates studied so far, a strong shift of the chemical potential at low hole doping is detected. However, the results for the inverse charge susceptibility at small shows a large variation between different doped cuprates. The results are discussed in view of various theoretical models. None of these models turns out to be satisfactory.
8 More- Received 10 June 2009
DOI:https://doi.org/10.1103/PhysRevB.80.165132
©2009 American Physical Society