Proximity and Josephson effects in superconductor - two dimensional electron gas planar junctions

TL;DR

This paper theoretically investigates the DC Josephson effect in a planar superconductor-2DEG junction, revealing how proximity-induced energy gaps and interface properties influence supercurrent behavior.

Contribution

It introduces a model describing the proximity effect and Josephson current in superconductor-2DEG planar junctions, highlighting the role of interface transmittance and Fermi velocity mismatch.

Findings

Energy gap in 2DEG depends on interface transmittance.

Region under superconductors acts like a superconductor with an effective order parameter.

Proximity effect modifies the excitation spectrum in the 2DEG.

Abstract

The DC Josephson effect is theoretically studied in a planar junction in which a two dimensional electron gas (2DEG) infinite in lateral directions is in contact with two superconducting electrodes placed on top of the 2DEG. An energy gap in the excitation spectrum is created in the 2DEG due to the proximity effect. It is shown that under certain conditions, the region of the 2DEG underneath the superconductors is analogous to a superconducting region with an order parameter $\varepsilon_g\exp(i\phi)$\/, where $\varepsilon_g~(\varepsilon_g<\Delta)$\/ depends on the interface transmittance and the Fermi velocity mismatch between the superconductors and the 2DEG.