Impact of vacancies on twisted bilayer graphene quantum point contacts

Abstract

We carry out an extensive numerical study of low-temperature electronic transport in quantum point contacts based on twisted bilayer graphene. Assuming ballistic electron dynamics, quantized plateaus in the conductance are observed in defect-free samples when the twisting angle is large enough. However, plateaus are smeared out and hardly noticeable on decreasing the angle. Close to the magic angle, the conductance around the charge neutrality point drops significantly and the quantization steps visible at higher angles are no longer appreciable. Furthermore, we consider the effects of a random distribution of vacancies on the quantum point contact. Whereas the electron-hole symmetry is broken in pristine samples, we find that this symmetry is restored upon increasing the concentration of vacancies. We explain this effect by a reduction of the effective interlayer coupling due to the presence of the vacancies.

References in corpus (31)

• Magic-angle graphene superlattices: a new platform for unconventional superconductivity
• Graphene Spintronics
• Kwant: a software package for quantum transport
• The electronic properties of bilayer graphene
• Flat Bands in Slightly Twisted Bilayer Graphene
• Disorder Induced Localized States in Graphene
• Quantum conductance of graphene nanoribbons with edge defects
• Higher-Order Topological Insulator in Twisted Bilayer Graphene
• Gate-controlled topological conducting channels in bilayer graphene
• Band structure and topological property of twisted double bilayer graphenes
• The crucial role of atomic corrugation on the flat bands and energy gaps of twisted bilayer graphene at the "magic angle" $\theta \sim 1.08^{\circ }$
• Quantized conductance of a suspended graphene nanoconstriction
• Electrostatically induced quantum point contact in bilayer graphene
• Electronic transport through bilayer graphene flakes
• Edge states and flat bands in graphene nanoribbons with arbitrary geometries
• Disorder in Twisted Bilayer Graphene
• Electronic Properties of Twisted Trilayer Graphene
• Topologically non-trivial valley states in bilayer graphene quantum point contacts
• DC conductivity of twisted bilayer graphene: Angle-dependent transport properties and effects of disorder
• Twisted bilayer zigzag-graphene nanoribbon junctions with tunable edge states
• Origin of conductance quantization in disordered graphene ribbons
• Minimum model for the electronic structure of twisted bilayer graphene and related structures
• Gate-controlled conductance through bilayer graphene ribbons
• Atomic-scale defects restricting structural superlubricity: Ab initio study study on the example of the twisted graphene bilayer
• Point Defects in Twisted Bilayer Graphene: A Density Functional Theory Study
• Emergent magnetic texture in driven twisted bilayer graphene
• One-dimensional moiré superlattices and flat bands in collapsed chiral carbon nanotubes
• Electronic conductance of twisted bilayer nanoribbon flakes
• Impurity scattering induced carrier transport in twisted bilayer graphene
• Universality of moiré physics in collapsed chiral carbon nanotubes
• Quantized electron transport through graphene nanoconstrictions