Energy loss study of the electronic structure of YBa2Cu3O7-δ high Tc superconductor

An electron energy loss investigation up to 40 eV of YBa2Cu3O7-δ (δ≈0.2) is presented. All structures are identified and the ε2 spectrum in the region 0-10 eV is accounted for by a simple convolution of occupied and empty densities of states. A sizeable temperature dependence of ε2, below and above Tc, involving Cu 3d-O 2p valence states is observed.