Rashba spin orbital coupling effect on the conductance of two-dimensional electron gas/insulator/noncentrosymmetric superconductor junction

We report a theoretical study on the tunneling conductance of two-dimensional electron gas/insulator/noncentrosymmetric superconductor (SC) junction, in which Rashba spin-orbital coupling (RSOC) exists in both sides of the junction and the SC lead has a mixed singlet and triplet superconducting correlation. Employing the extended Blonder-Tinkham-Klapwijk formalism, we found that RSOC in either side of the junction can enhance or suppress the conductance, depending on the junction parameters such as the Fermi wave-vectors of the leads and the insulator barrier strength between the two leads. This is different from the effect of a ferromagnetic lead. It is also found that the conductance spectra exhibit distinctive peaks and turning points, which are very useful for determining the relative strength of the singlet and triplet gaps of the SC lead, as well as the RSOC constant of the noncentrosymmetric SC from tunneling conductance measurements. © 2009 The Physical Society of Japan.