Shot noise in NS junctions with Weyl superconductor

TL;DR

This paper explores how shot noise measurements in N-WS junctions reveal the effects of surface states and superconductivity in Weyl semimetals, highlighting the influence of surface orientation on transport properties.

Contribution

It introduces the use of shot noise analysis to probe intrinsic superconductivity and surface states in Weyl semimetals, showing orientation-dependent effects on noise characteristics.

Findings

Shot noise depends on surface orientation relative to tunneling direction.

Low energy states reduce shot noise power at decreasing voltages.

Surface states with flat bands significantly influence transport properties.

Abstract

We demonstrate that current-current correlations (in particular the shot noise), can be used to study the intrinsic superconductivity in a slightly doped Weyl semi-metal. The systems studied is an N-WS tunneling junction where the left electrode is a normal metal while the right electrode is a Weyl superconductor (WS). The superconductivity supports surface state with crossed flat bands thereby impact the low energy spectrum. This spectrum displays a modified density of states in the gap region that strongly affects transport characteristics of the N-WS junction. The Fano factor is calculated as function of the applied bias, and shown to be dependent essentially on the orientation of the surface of WS relative to the tunneling direction. If this orientation supports the occurrence of low energy state, then the shot noise power decreases with decreasing voltage, a property similar to that prevailing in a junction with Majorana bound state.