Point-Contact Tunneling Involving Low-Dimensional Spin-Triplet Superconductors

We modify and extend previous microscopic calculations of tunneling in superconducting junctions based on a nonequilibrium Green function formalism to include the case of spin-triplet pairing. We show that distinctive features are present in the $I\mathrm{\text{−}}V$ characteristics of different kinds of junctions, in particular, when the effects of magnetic fields are taken into account, that permit to identify the type of pairing. We discuss the relevance of these results in the context of quasi-one-dimensional organic superconductors such as $(\mathrm{TMTSF}{)}_2{\mathrm{PF}}_6$ and layered compounds like ${{\mathrm{Sr}}_{\mathrm{2}}\mathrm{RuO}}_4$.

Figure 1

Three different sets of $I\mathrm{\text{−}}V$ characteristics vertically displaced for clarity. From top to bottom: (a) N-S junction, (b) N-T junction, and (c) S-T junction. The solid (dashed) lines correspond to the characteristics in the absence (presence) of an oriented magnetic field (see text for details). In all three, sets are plotted as reference to the curve for the N-N case (diagonal straight dotted lines) and in the third one the curve for a S-S junction is also given.