Current-phase relation in Nb-Al based SINIS-type Josephson junctions

The supercurrent-phase relation (CPR) of NbAl based Josephson elements of superconductor/insulator/normal conductor/insulator/superconductor-type is deduced from impedance measurements of the phase-biased junction. The chosen temperature range from 1.9 to 8.0 K covers the superconducting transition of the aluminum interlayer below which a pronounced non-harmonic CPR is found. At temperatures higher than the corresponding critical temperature, the CPR did not deviate significantly from purely harmonic shape. Both results are in agreement with theoretical predictions.