Interface mechanism of Co/BiSrCaCuO system studied by XPS and UPS techniques

An electronic structure study of the Co/BiSrCaCuO system has been carried out using XPS and UPS techniques. Changes in copper core level spectra suggest rapid depression in the critical temperature. The destructivity of superconductivity and the growth of the Co metal on the substrate is further suggested by UPS. Qualitative analysis of the core levels indicates island type of growth on the substrate. A new mechanism is suggested for the interfacial reaction of Co/BiSrCaCuO being identical to the one in doped systems. Co ions as impurities are found to reside in Cu-O planes. It indicates that impurities in the plane site reduce the critical temperature, suggesting that Cu-O planes play an important role in the existence of superconductivity in the superconducting compounds. Our claims about the mechanism and behaviour of Co in the system are partly based on speculation.