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F. Libisch:
"Graphene quantum dots: confining Dirac electrons";
Vortrag: Solids-4-Fun Summer school, Waidhofen an der Ybbs (eingeladen); 02.07.2018 - 06.07.2018.

The special properties of graphene have created wide interest inpossible graphene-based nanoelectronic devices. A theoretical
understanding of the electronic structure of graphene in different chemical environments, and ways to tailor them, are crucial for future
device applications. We investigate the electronic properties of nanostructured graphene using tight binding. Density
functional theory calculations in combination with Wannier projections allow for quantitatively accurate tight binding
parameters to simulate substrate effects.

Sandwiching graphene between layers of hexagonal boron nitride protects the material against chemical residuals
of the etching chemistry, allowing for the experimental observations of ballistic scattering. Unfortunately, even in
the absence of bulk disorder the properties of lithographically patterned graphene quantum dots are still dominated by
the edge roughness induced by the device fabrication process. To demonstrate the unique symmetry properties of
graphene therefore requires dot geometries without physical edges. We combine a magnetic field with the tip of a
scanning tunneling microscope to create a smooth confinement. The resulting potential well allows for localizing
states in the Landau gaps of bulk graphene. Such devices open a pathway towards applications of graphene in
quantum information technologies.