Magnetoconductance of the Corbino disk in graphene: Chiral tunneling and quantum interference in the bilayer case

Grzegorz Rut; Adam Rycerz

doi:10.1088/0953-8984/26/48/485301

paper

Magnetoconductance of the Corbino disk in graphene: Chiral tunneling and quantum interference in the bilayer case

arXiv:1405.4908 · doi:10.1088/0953-8984/26/48/485301

Abstract

Quantum transport through an impurity-free Corbino disk in bilayer graphene is investigated analytically, by the mode-matching method for effective Dirac equation, in the presence of uniform magnetic fields. Similarly as in the monolayer case (see Refs. [1,2]), conductance at the Dirac point shows oscillations with the flux piercing the disk area $Φ_{D}$ characterized by the period $Φ_{0} = 2 (h / e) ln (R_{o} / R_{i})$ , where $R_{o}$ ( $R_{i}$ ) is the outer (inner) disk radius. The oscillations magnitude depends either on the radii ratio or on the physical disk size, with the condition for maximal oscillations reading $R_{o} / R_{i} ≃ [R_{i} t_{⊥} / (2ℏ v_{F})]^{4/ p}$ (for $R_{o} / R_{i} ≫ 1$ ), where $t_{⊥}$ is the interlayer hopping integral, $v_{F}$ is the Fermi velocity in graphene, and $p$ is an {\em even} integer. {\em Odd}-integer values of $p$ correspond to vanishing oscillations for the normal Corbino setup, or to oscillations frequency doubling for the Andreev-Corbino setup. At higher Landau levels (LLs) magnetoconductance behaves almost identically in the monolayer and bilayer cases. A brief comparison with the Corbino disk in 2DEG is also provided in order to illustrate the role of chiral tunneling in graphene.

arXiv commentTypos corrected; acknowledgment added. RevTeX, 13 pages, 7 figures

Magnetoconductance of the Corbino disk in graphene: Chiral tunneling and quantum interference in the bilayer case

Abstract

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