Current-voltage characteristics of tunnel junctions between superconductors with anisotropic pairing

Charge transfer in tunnel junctions between superconductors with anisotropic singlet pairing is considered theoretically on the basis of the Eilenberger equations for the quasiclassical Green's functions. New singularities of the current-voltage characteristics, which are characteristic of the case of anisotropic pairing, are treated analytically assuming that the electrons reflect specularly from the boundaries of the tunnel barrier. All four contributions to the tunneling current are investigated. Two of them describe Josephson tunneling, and the other two contributions correspond to the quasiparticle current (the last term appears only for a variable voltage). Different dependences of the order parameter on the momentum directions in the interior of the superconductors and different orientations of the crystal axes relative to the junction plane are considered. The results of numerical calculations of the current-voltage characteristics for several particular cases are presented. (C) 1997 American Institute of Physics.