X-ray absorption study of YBa2−xLaxCu3Oy

The O-1s and Cu-2p3/2 X-ray absorption near-edge spectra of YBa2−xLaxCu3Oy have been measured by using synchrotron radiation. The total number of holes, as derived from the spectral data, decreases linearly with the increase of La content, x. The holes of O(4) are altered slightly, as compared to the decrease in the holes of the CuO2 planes, by the La3+ substitution of Ba2+. The main effect of La in YBa2−xLaxCu3Oy is to change the electronic structure in the CuO2 planes so that the concentration of the hole states is reduced.