Structural studies of the effects of silver and gold on the YBaCuO superconducting films formed from layer structures

Abstract

Superconducting YBaCuO films have recently been formed using both Ag/Cu/BaO/Y2O3/MgO and Au/Cu/BaO/Y2O 3/MgO structures, where MgO is the substrate. The addition of a silver layer in the starting structure improves the film resistances from those using the Cu/BaO/Y2 O3 /MgO structure, especially at lower annealing temperatures. This allows the formation of superconducting films between annealing temperatures of 750 and 900°C, all with an onset above 85 K. The transition into full superconductive state, however, broadens with decreasing annealing temperatures, with zero resistance between 80 and 60 K. This dependence on annealing temperatures is studied by x-ray diffraction, which shows the diminishing signals of the superconducting YBa2 Cu 3 O7 phase at reduced annealing temperatures. A study of the surface morphology provides further information regarding the roles of silver and gold on the superconducting films formed.