Sub-Sharvin conductance and incoherent shot-noise in graphene disks at magnetic field

TL;DR

This paper investigates the unique conductance and shot-noise behavior in highly-doped graphene disks under high magnetic fields, revealing a graphene-specific Fano factor near 0.56 through quantum transport simulations.

Contribution

It introduces a model for incoherent scattering in graphene disks and predicts a distinctive shot-noise feature at zero conductance under high magnetic fields.

Findings

Fano factor approaches 0.56 when conductance drops to zero.

Weak dependence of Fano factor on disk radii ratio.

Behavior influenced by voltage and electrostatic potential shape.

Abstract

Highly-doped graphene samples show the conductance reduced and the shot-noise power enhanced compared to standard ballistic systems in two-dimensional electron gas. These features can be understood within a model assuming incoherent scattering of Dirac electrons between two interfaces separating the sample and the leads. Here we find, by adopting the above-mentioned model for the edge-free (Corbino) geometry and by means of the computer simulation of quantum transport, that another graphene-specific feature should be observable when the current flow through a doped disk is blocked by high magnetic field. In case the conductance drops to zero, the Fano factor approaches the value of $F\approx{}0.56$, with a very weak dependence on the disk radii ratio. The role of finite source-drain voltages and the system behavior upon tuning the electrostatic potential barrier from a rectangular to parabolic shape are also discussed.