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F. Libisch:
"Modeling and probing the superstructure of graphene on hexagonal boron nitride";
Vortrag: Gastvortrag am Institut für Physik, Graz (eingeladen); 28.06.2018 - 29.06.2018.

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 ~13 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 interaction 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)