Modulation of the Josephson current of Nb/AlO{sub}x/Nb single and double junctions by two-dimensional scan of the external magnetic field

摘要

Josephson current of superconducting junctions can be modulated by an external magnetic field. From this modulation pattern of the Josephson current, uniformity of the tunnel barrier can be confirmed. The modulation of the Josephson current I{sub}c of the superconducting junctions is usually observed by one-dimensional scan of the applied magnetic field. In this paper, using two pairs of the Helmholz coils, the external magnetic field H is scanned in two dimensions and the two-dimensional surfaces of the I{sub}c-H dependence are first measured. In this research, we measure the modulation of the DC Josephson currents of Nb/AlO{sub}x/Nb junctions and Nb/AlO{sub}x/Nb/AlO{sub}x/Nb junctions by two dimensional scan of the external magnetic field.