X-ray absorption study of oxygen in the high-Tc superconductor Bi2Sr2CaCu2O8 near the interfaces to Cu, Ag and Au

Abstract The influence on O 2p holes in single crystalline Bi 2 Sr 2 CaCu 2 O 8 upon the interface formation to Cu, Ag and Au has been studied by O K edge X-ray absorption measurements. It was found that Cu reduces the amount of doping induced O 2p holes significantly in the vicinity of the interface, whereas Ag and Au gave a much smaller reduction of these states. Photoemission spectra confirmed previous findings that Cu causes a strong chemical reaction at the BiO surface of Bi 2 Sr 2 CaCu 2 O 8 , in contrast to Ag and Au which induced only a minimal reaction. The results support the opinion that the BiO layers are essential for the doping of the CuO 2 layers in Bi 2 Sr 2 CaCu 2 O 8 .