Y-Ba-Cu-O/AlO_x/Nb Josephson Tunnel Junctions

Abstract

We have fabricated Y-Ba-Cu-O/AlO x /Nb Josephson tunnel junctions using electron-beam evaporation of Al and Nb films and natural oxidation. Superconducting Josephson current, hysteresis, and rf-induced voltage steps at a voltage greater than 0.4 mV have been clearly observed at 4.2 K. Moreover, rf-induced subharmonic steps have appeared. Magnetic field dependence of the superconducting Josephson current has also been studied.