Determination of the temperature dependence of the penetration depth of Nb in Nb/AlO(sub x)/Nb Josephson junctions from a resistive measurement in a magnetic field

摘要

The temperature dependence of the penetration depth of Nb films was determined from resistive transitions of Nb/AlO(sub x)/Nb Josephson junctions in a constant magnetic field applied parallel to the junction planes. Distinct resistance peaks were observed as temperature decreases and those peaks were found to appear when the total flux threading the junction equals an integral multiple of the flux quantum. From this condition, the authors have determined the penetration depth at those peak positions. The temperature dependence was well described by the either dirty local limit or the two-fluid model. This method can be useful for highly fluctuating system like high-temperature superconductors.