AQP seminaari: Transport through Mono- and Bilayer Graphene Nanoconstrictions

Aalto Quantum Physics -seminaari (Nanotalo). Puhuja: Florian Libisch ( Institute for Theoretical Physics, Vienna University of Technology )

Quantum point contacts are cornerstones of mesoscopic physics and central building blocks for quantum electronics. Although the Fermi wavelength in high-quality bulk graphene can be tuned up to hundreds of nanometres, the observation of quantum confinement of Dirac electrons in nanostructured monolayer graphene has proven surprisingly challenging. Edge scattering at lithographically defined monolayer graphene constrictions washes out quantization steps. By contrast, bilayer graphene allows for electrostatically defining a constriction featuring prominent size quantization signatures. Using a perpendicular magnetic field, we observe the adiabatic evolution of size quantization features to the Landau regime. We find an intricate interweaving pattern originating from the valley symmetry and exceptional band structure of graphene. We compare experimental data and simulations in all cases, and find excellent agreement.

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