Shot noise of the conductance through a superconducting barrier in graphene

TL;DR

This paper explores how superconducting barriers affect conductance and shot noise in graphene, revealing distinct behaviors depending on the presence of specular Andreev reflection and highlighting the influence of barrier parameters.

Contribution

The study develops a BTK-based theoretical model for superconducting graphene, comparing transport with and without specular Andreev reflection, and analyzes shot noise behavior.

Findings

Shot noise is suppressed with superconducting gating due to increased tunneling channels.

Shot noise sensitivity varies with potential strength and barrier width in different reflection regimes.

Total transmission at specific parameters reduces shot noise and enhances conductance.

Abstract

We investigated the conductance and shot noise properties of quasiparticle-transport through a superconducting barrier in graphene. Based on the Blonder, Tinkham, and Klapwijk (BTK) formulation, the theory to investigate the transport properties in the superconductive graphene is developed. In comparison, we considered the two cases that are the transport in the presence and absence of the specular Andreev reflection. It is shown that the conductance and shot noise exhibit essentially different features in the two cases. It is found that the shot noise is suppressed as a result of more tunneling channels contributing to the transport when the superconducting gate is applied. The dependence of the shot noise behavior on the potential strength and the width of the superconducting barrier differs in the two cases. In the presence of the specular Andreev reflection, the shot noise spectrum is more sensitive to the potential strength and the width of the superconducting barrier. In both of the two cases, total transmission occurs at a certain parameter setting, which contributes greatly to the conductance and suppresses the shot noise at the same time.