Anisotropy in the near-edge absorption fine structure of YBa2Cu3O7-

We have observed orientational anisotropy of the near-edge absorption fine structure for the Cu 2p and O 1s excitations in single crystals of YBa2Cu3O7- using electron-energy-loss spectroscopy. The O 1s absorption results suggest that O-derived holes near the Fermi level have px,y symmetry. The Cu 2p edge is weakly anisotropic and consistent with some holes having dZ2 symmetry. © 1988 The American Physical Society.