Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 80: Graphene

TT 80.11: Talk

Thursday, March 15, 2018, 12:15–12:30, H 3005

Husimi Projections in Graphene: Measuring Klein Tunneling — •George Datseris, Theo Geisel, and Ragnar Fleischmann — Max Planck Institute for Dynamics and Self-Organization, Goettingen, Germany

One of the most intriguing electronic properties of graphene is the occurrence of Klein Tunneling: ballistic conduction electrons are expected to show full transmission on normal incidence on almost arbitrary potential barriers. On oblique incidence the transmission decays rapidly, leading to a collimation effect at the barrier. Recently graphene experiments have reached the ballistic regime and measurements confirmed collimated transmission, but measuring the characteristic transmission versus the angle of incidence T(θ) directly seems to be still out of reach. One reason for this is that it is hard to define an angle of incidence (and even hard to measure) in both experiments and tight-binding calculations.

In order to analyse T(θ) in a tight-binding quantum transport model we modify and employ the Husimi projection. We combine this approach with a Landauer-Büttiker type description of e.g. a graphene pn-junction. This allows us to observe T(θ) in a controlled but experimentally relevant model. In the absence of a magnetic field our results almost perfectly match the semi-classically derived formulas for transmission found in the literature. In the presence of a magnetic field, however, our results show strong differences from the semi-classical predictions.