Magnetoconductance of the Corbino disk in graphene

TL;DR

This paper investigates magnetoconductance oscillations in a graphene Corbino disk, revealing flux-dependent conductance patterns at the Dirac point and their dependence on disk geometry and doping levels.

Contribution

It provides a detailed analysis of flux-induced conductance oscillations in graphene Corbino disks, including the effects of doping and geometry, which was not previously characterized.

Findings

Conductance oscillations with flux period =(2h/e)\,ln(R_o/R_i) at the Dirac point.

Oscillation magnitude increases with the radii ratio, exceeding 10% for R_o/R_i  5.

Oscillations persist at finite doping within a limited flux range, with a crossover to ballistic transport at high doping and weak fields.

Abstract

Electron transport through the Corbino disk in graphene is studied in the presence of uniform magnetic fields. At the Dirac point, we observe conductance oscillations with the flux piercing the disk area $\Phi_d$, characterized by the period $\Phi_0=(2h/e)\ln(R_o/R_i)$, where $R_o$ ($R_i$) is the outer (inner) disk radius. The oscillations magnitude increase with the radii ratio and exceed 10% of the average conductance for $R_o/R_i\geqslant 5$ in the case of the normal Corbino setup, or for $R_o/R_i\geqslant 2.2$ in the case of the Andreev-Corbino setup. At a finite but weak doping, the oscillations still appear in a limited range of $|\Phi_d|\leqslant\Phi_d^{max}$, away from which the conductance is strongly suppressed. At large dopings and weak fields we identify the crossover to a normal ballistic transport regime.