INTERFACE MECHANISM OF CO BISRCACUO SYSTEM STUDIED BY XPS AND UPS TECHNIQUES/

An electronic structure study of the Co/BiSrCaCuO system has been carr ied out using XPS and UPS techniques. Changes in copper core level spe ctra suggest rapid depression in the critical temperature. The destruc tivity of superconductivity and the growth of the Co metal on the subs trate is further suggested by UPS. Qualitative analysis of the core le vels indicates island type of growth on the substrate. A new mechanism is suggested for the interfacial reaction of Co/BiSrCaCuO being ident ical to the one in doped systems. Co ions as impurities are found to r eside in Cu-O planes. It indicates that impurities in the plane site r educe the critical temperature, suggesting that Cu-O planes play an im portant role in the existence of superconductivity in the superconduct ing compounds. Our claims about the mechanism and behaviour of Co in t he system are partly based on speculation.