Two-dimensional magnetic field dependence of Josephson current and resonant current steps at finite voltage of square shape superconducting tunnel junctions

Abstract

In this article, modulation characteristics of Josephson current through square shape niobium/aluminum-oxide/niobium superconducting junction by two-dimensional scanning of external magnetic field have been studied. Two pairs of Helmholtz coils are controlled by two current sources with general purpose interface bus system to obtain the magnetic field dependence automatically. The distribution of Josephson current density inside the square junction area is obtained. The 2-D magnetic field dependences of the resonant current steps of the current-voltage characteristics of the Nb/Al-oxide/Nb tunnel junction have also been measured using the junction voltage as the parameter.