Switching Phenomenon in I-V Curves for Superconducting BaPb_1-xBi_xO₃ Films

Abstract

A novel voltage switching effect has been reported for superconducting polycrystalline BaPb 0.7 Bi 0.3 O 3 (BPB) films possessing two dimensional boundary-Josephson-junctions (BJJ) arrays. I-V curves are measured for a BPB film with a perpendicular control-current flow pattern. Two I-V curve phenomena are observed. One is a voltage switching effect by an integral multiple of the superconducting energy gap voltage. The other is that the voltage states in the I-V curves are elongated beyond the V-axis. The switching phenomena are investigated in detail by varying the control current and the line width of the BPB cross patterns. The results obtained verify the hypothesis that the voltage switching is caused by diagonally connected BJJs in the voltage state due to electromagnetic coupling among the BJJs.