[Zurück]

B. Terrés, S. Engels, D. Jörger, L. Chizhova, F. Libisch, J. Burgdörfer, C Stampfer:
"Size quantization signatures in graphene quantum point contacts";
Poster: Graphene week 2015, Manchester; 22.06.2015 - 26.06.2015.

Quantum point contacts form a cornerstone of mesoscopic physics as central building
blocks for quantum electronic devices. Graphene shows a number of exceptional properties
but the demonstration of graphene quantum point contacts has proven very challenging.
Recent developments in the fabrication of high-mobility graphene-hexagonal boron nitride
sandwich structures have improved the chances to observe quantum confinement of Dirac
electrons in quasi-one dimensional (1D) graphene systems.
Here we present joint experimental and theoretical work on ballistic transport of confined
Dirac fermions in graphene quantum point contacts [Fig. 1a,b]. At high charge carrier
densities, measurements agree excellently with theoretical simulations. Deviations from the
expected linear behavior at low carrier densities emerge due to localized states at the
edges, allowing the direct probing of trap states by transport measurements. Reproducible
kinks in the conductance are associated with size quantization in the quantum point
contact [Fig. 1c]. Comparing the evolution of the observed kinks with magnetic field to
theoretical predictions for one-dimensional confined states in graphene confirms size
quantization as their origin.

http://publik.tuwien.ac.at/files/PubDat_247245.pdf