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N. Freitag, T. Reisch, F. Libisch, P. Nemes-Incze, J. Burgdörfer, M. Morgenstern:
"Edge-free graphene quantum dots on hexagonal boron nitride";
Vortrag: CCP 2018, Davis, Californien, USA; 29.07.2018 - 03.08.2018.

Graphene offers two binary degrees: the electron spin and the valley. Efficient spin control has been
demonstrated in many solid-state systems, whereas exploitation of the valley has only recently been
started, albeit without control at the single-electron level. Here, we show that van der Waals stacking of
graphene onto hexagonal boron nitride offers a natural platform for valley control. Aligning the two layers
yields a superstructure with a periodicity of 1̃3 nanometers. By combining electric and magnetic fields,
we can smoothly confine electrons within the moire superstructure in both theory and experiment, and
show that the smooth confinement allows for controlled manipulation of the valley degree of freedom
[1].
Simulating this systems requires both high-level approaches vor describing the Van der Waals inter-
action between the layers, as well as large-scale tight binding and molecular dynamics techniques to
describe the entire quantum dot. The resulting multi-scale model includes strain effects within the
graphene membrane, the interaction with the substrate and the combined electric and magnetic fields.
Our results compare well to direct measurements of the quantum dot states, yielding exquisite details
of the graphene - boron nitride interaction.
[1]N. M. Freitag et al, Nature Nanotechnology 13, 392-397 (2018)