Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 15: Transport: Graphene and Carbon Nanostructures (jointly with DY, DS, HL, MA, O)
TT 15.3: Vortrag
Montag, 20. März 2017, 15:30–15:45, HSZ 204
Probing electronic wave functions in a nanotube quantum dot via conductance in a magnetic field — Magdalena Marganska1, Alois Dirnaichner1,2, Daniel R. Schmid2, Peter L. Stiller2, Christoph Strunk2, Milena Grifoni1, and •Andreas K. Hüttel2 — 1Institute for Theoretical Physics, Universität Regensburg, Regensburg, Germany — 2Institute for Experimental and Applied Physics, Universität Regensburg, Regensburg, Germany
The tunneling of electrons through a contact between two systems depends on the overlap of their electronic wave functions. In quantum dots the overlap is often tuned via the height of tunneling barriers. Conversely, in carbon nanotubes the unique combination of cylindrical topology and honeycomb atomic lattice allows for a manipulation of the longitudinal component of the electronic wave function via a parallel magnetic field. The amplitude of the wave function at the point of contact with the leads is directly reflected in the coupling strength. Experimentally, we detect the changes in the electronic wave function through the evolution of conductance resonances corresponding to single particle quantum states with magnetic field. The magnitude of the magnetic field in our experiment, up to 17 T, allows us to confirm our prediction of the very different behaviour of the two valley states. The K’ valley states experience a strengthening of the tunnel coupling at low magnetic field, followed by subsequent decoupling. In contrast, the K valley states decouple from the leads monotonically, and coupling becomes unmeasurably small already for moderate magnetic fields.