PHOTOEMISSION SPECTROSCOPY OF YBA2CU3O6+X

High-resolution angle-integrated photoemission measurements were made on a sample of the compound Y//1Ba//2Cu//3O//6// plus //x, for which it was shown that the onset of superconductivity was as high as 93 K. The density of states associated with the Cu 3d levels appears in an intense band about 4 eV wide beginning about 1. 5 eV below the Fermi level. A small wing of this band extends up to the Fermi level, where the density of states is relatively low. These results are in good agreement with the projected density of states of Cu as obtained in recent calculations.