Proximity effect in a superconductor/two-dimensional electron gas junction with Rashba spin–orbit coupling

We study theoretically the proximity effect in a conventional superconductor/two-dimensional electron gas (2DEG) junction in the presence of Rashba spin-orbit coupling (RSOC). By means of the fluctuation-dissipation theorem and Green's function method, the superconductivity correlation function in the 2DEG region could be resolved in the clean limit. It is found that the perpendicular injection of quasiparticles through the interface can only induce singlet superconductivity correlation in the 2DEG region and in this case the RSOC of the 2DEG can hardly affect the proximity effect, whereas the oblique injection of quasiparticles can give rise to not only singlet but also triplet superconductivity correlations in the RSOC region. The latter correlation exhibits a damped oscillating behavior and even reverses its sign. In the case of perpendicular injection, triplet superconductivity correlation can also be induced in the 2DEG region as long as a uniform ferromagnetic interaction is present.