Abstract
We report on an x-ray absorption and resonant photoemission study on single crystals of the high- cuprates and . Using an intrinsic energy reference, we find that the chemical potential of lies near the top of the valence band whereas in it is situated near the bottom of the conduction band. The data clearly establish that the introduction of Ce in results in electrons being doped into the planes. We infer that the states closest to the chemical potential have a Cu singlet origin in and a singlet origin in .
- Received 2 February 2003
DOI:https://doi.org/10.1103/PhysRevLett.90.247005
©2003 American Physical Society