Josephson effect in silicene-based SNS Josephson junction: Andreev reflection and free energy

TL;DR

This paper explores the Josephson effect in silicene-based SNS junctions, focusing on Andreev reflection, free energy, and the emergence of $ $-junctions under electric fields and light, revealing unique transport properties and phase transitions.

Contribution

It provides new insights into Andreev reflection and phase behavior in silicene SNS junctions influenced by electric fields and light, highlighting the role of dynamical polarization and impurities.

Findings

Complete Andreev reflection occurs even in clean interfaces without Fermi wave vector mismatch.

Electric fields and light induce $ $-junctions and phase transitions in silicene.

Impurities affect transport properties and valley relaxation in the junction.

Abstract

We investigate the Josephson effcet in superconductor-normal-superconductor junction (SNS) base on the doped unbiased silicene under the perpendicular electric field and off-resonance circularly polarized light. The Andreev reflection (including the retroreflection and specular one) during the subgap transport, the free energy, and the reversal of the Josephson effect as well as the emergence of $\phi_{0}$-junction are exploited. The Andreev reflection is complete in the NS interface even for the clean interface and without the Fermi wave vector mismatch, which is opposite to the case of ferromagnet-superconductor interface. The important role played by the dynamical polarization of the degrees of freedom to the $0-\pi$ transition and the generation of $\phi_{0}$-junction are mentioned in this paper. The scattering by the charged impurity in the substrate affects the transport properties in the bulk as well as the valley relaxation, which can be taken into consider by the macroscopic wave function. In short junction limit, the approximated results about the Andreev level and free energy are also discussed. Beside the low-energy limit of the tight-binding model, the finite-size effect need to be taken into account as long as the spacing model is much larger than the superconducting gap.