Transport properties of an electron-hole bilayer/superconductor hybrid junction

Research paper by D. Bercioux, F. S. Bergeret, T. M. Klapwijk

Indexed on: 30 Mar '17Published on: 30 Mar '17Published in: arXiv - Physics - Superconductivity


We investigate the transport properties of a junction consisting of an electron-hole bilayer in contact with normal and superconducting leads. The electro-hole bilayer is considered as a semi-metal with two electronic bands. We assume that in the region between the contacts the system hosts an exciton condensate described by a BCS-like model with a gap $\Gamma$ in the quasiparticle density of states. We first discuss how the subgap electronic transport through the junction is mainly governed by the interplay between two kinds of reflection processes at the interfaces: The standard Andreev reflection at the interface between the superconductor and the exciton condensate, and a coherent crossed reflection at the semi-metal/exciton-condensate interface that converts electrons from one layer into the other. We show that the differential conductance of the junction shows a minimum at voltages of the order of $\Gamma/e$. Such a minimum can be seen as a hallmark of the existence the gapped excitonic state.