Testing superconducting pairing symmetry in multiterminal junctions

Abstract

An approach to distinguish p-wave from s-wave superconducting pairing symmetry and thus to select potential platforms for Majorana fermions is proposed in terms of electronic transport differences in a four terminal junction consisting of superconducting (S) and normal (N) terminals in the diffusive regime. The Keldysh Green’s function equations are derived in the θ-parametrisation, incorporating terms previously neglected in the literature. A stable procedure to solve these equations is presented. The supercurrent and differential conductance between two superconducting electrodes were calculated in the Keldysh–Usadel approximation. The N-terminals can be used to manipulate the energy distribution functions of electrons in the junction in order to control the overall charge transport. Our results provide a new experimental test to detect potential p-wave superconductivity. In fact, we show that the differential conductance of junctions containing p-wave superconductors is distinctly different from the differential conductance in junctions with s-wave superconductors, whereas the supercurrent through the junction is qualitatively similar. This is of importance for the search for Majorana fermions since it may help to design experiments to detect signatures of p-wave symmetry, which may lead to potential platforms for Majorana fermions.