Josephson and single-particle currents between partially dielectricized superconductors with charge-density waves

Abstract

The amplitudes of the nonstationary Josephson current I1, the interference current I2, and the quasiparticle current J through symmetric and asymmetric tunnel junctions, including superconductors with charge density waves, are calculated. In the symmetric (s) case the dependence of the Josephson current Is1 on the voltage V on the junction has a logarithmic singularity at |eV|=2Δ, Δ+D, and 2D, where \(D = \sqrt {(\Delta ^2 + \Sigma ^2 )} \), Δ and Σ are the superconducting and dielectric order parameters, and e is the unit charge. At temperatures T≠0 jumps appear in the current-voltage characteristics Is1(V) at |eV|=D−Δ. Jumps and singularities are observed in the currents Is2 and Js at the same voltages at which singularities and jumps appear in Is1, respectively. In the nonsymmetric (ns) junctions which include an ordinary superconductor, singularities and jumps occur at |eV|=D+ΔBCS, Δ+ΔBCS, and (for T≠0) |D−ΔBCS| and |Δ−ΔBCS|, where ΔBCS is the order parameter of an ordinary superconductor. The quasiparticle current Jns is an asymmetric function of the voltage V and does not depend on the sign of Σ. The results are compared with experiment.