Aharonov-Bohm oscillations and magnetic focusing in ballistic graphene rings

Abstract

We present low-temperature magnetotransport measurements on graphene rings encapsulated in hexagonal boron nitride. We investigate phase-coherent transport and show Aharonov-Bohm (AB) oscillations in quasi-ballistic graphene rings with hard confinement. In particular, we report on the observation of $h/e$, $h/2e$ and $h/3e$ conductance oscillations. Moreover we show signatures of magnetic focusing effects at small magnetic fields confirming ballistic transport. We perform tight binding calculations which allow to reproduce all significant features of our experimental findings and enable a deeper understanding of the underlying physics. Finally, we report on the observation of the AB conductance oscillations in the quantum Hall regime at reasonable high magnetic fields, where we find regions with enhanced AB oscillation visibility with values up to $0.7$%. These oscillations are well explained by taking disorder into account allowing for a coexistence of hard and soft-wall confinement.

arXiv comment28 pages, 8 figures

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• Dirac electrons in quantum rings
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• Gauge-underdetermination and shades of locality in the Aharonov-Bohm effect
• Manipulating electron waves in graphene using carbon nanotube gating
• Spin inversion in fluorinated graphene n-p junction
• Klein tunneling degradation and enhanced Fabry-Pérot interference in graphene/h-BN moiré-superlattice devices
• Strong Aharonov-Bohm quantum interference in simply-connected LaAlO${}_3$/SrTiO${}_3$ structures
• Four-band effective square lattice model for Bernal-stacked bilayer graphene
• Weak localization as probe of spin-orbit-induced spin-split bands in bilayer graphene proximity coupled to WSe${}_2$
• Asymmetric-gate Mach--Zehnder interferometry in graphene: Multi-path conductance oscillations and visibility characteristics
• Electrostatic gate-controlled quantum interference in a high-mobility two-dimensional electron gas at the (La${}_{0.3}$Sr${}_{0.7}$)(Al${}_{0.65}$Ta${}_{0.35}$)O${}_3$/SrTiO${}_3$ interface
• Electron-hole Hybridization in Bilayer Graphene