LEED and spectroscopic studies of the atomic and electronic structure of La2Cu2O5

Abstract Experimental investigation of “as grown” (001) surfaces of non-superconducting La 2 Cu 2 O 5 single crystals have been carried out by UPS, XPS, AES, EELS and LEED techniques. Clean surfaces of La 2 Cu 2 O 5 were obtained by annealing in oxygen and in situ in UHV. It is established by LEED and Auger spectroscopy that these (001) surfaces are non-reconstructed and their composition is close to stoichiometry. The UPS spectra of valence band and XPS spectra of O 1s, Cu 2p and La 3d are similar to La 2 CuO 4 ; however, even moderate annealing of the crystal at about 800 K (in UHV) partially reduces divalent Cu on the surface, changing the UPS and Cu 2p XPS spectra.