Evidence For 3d9-ligand Hole Induced By Doping In Bi-sr-ca-cu-o and Tl-ca-ba-cu-o

In this work an investigation of Cu L3 x-ray absorption spectra XAS of the new high-Tc compounds Bi-Sr-Ca-Cu-0 and Tl-Ca-Ba-Cu-0 is presented. The measured spectra give experimental evidence that the states induced by cation doping of the copper oxides have the 3d9L (where the & indicates a hole in the ligand orbital) configuration. Moreover the weight of these states has been found to be correlated with the different critical temperatures. This is the same behaviour previously found in the case of superconducting compounds Y-Ba-Cu-0 and Lu-Sr-Cu-0