Current-voltage characteristics of superconductor-normal metal-superconductor junctions

We develop a theory of current-voltage (I-U) characteristics for superconductor-normal metal-superconductor (SNS) junctions. At small voltages and sufficiently low temperatures the I-U characteristics of the junction is controlled by the inelastic relaxation time tau in. In particular, the linear conductance is proportional to tau in. In this regime the I-U characteristics can be expressed solely in terms of dependence of the density of states in the normal region nu(chi) on the phase difference of the order parameter across the junction. In contrast, at large voltages the I-U characteristics of the device is controlled by the elastic relaxation time tau el, which is much smaller than the inelastic one.(c) 2023 Elsevier Inc. All rights reserved.