Effects of Oxygen-Potential-Controlled Annealing on the Superconducting Properties of (Bi, Pb)₂Sr₂Ca₂Cu₃O_y Thin Films

Abstract

The oxygen potential of thin films consisting of monophasic (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O y was controlled by annealing them under various oxygen partial pressures. The T c of (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O y was found to decrease monotonously with decreasing oxygen potential. However, T c did not change when annealed under higher oxygen pressure up to 2.9×10 4 torr. The carrier concentration was found to change with oxygen partial pressure, implying that oxygen supplies the carrier. An optimum range of the carrier concentration exists for attaining the highest T c . This finding is consistent with those of other high T c hole-type superconductors.