Regensburg 2016 – scientific programme
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DS: Fachverband Dünne Schichten
DS 7: Graphene: Transport
(Joint session of DS, DY, HL, MA, O and TT organized by HL)
DS 7.4: Talk
Monday, March 7, 2016, 15:45–16:00, H17
Transport studies in laterally density-modulated graphene-boron nitride-heterostructures — •Martin Drienovsky1, Christian Baumgartner1, Felix Simbürger1, Takashi Taniguchi3, Kenji Watanabe3, Ming-Hao Liu2, Fedor Tkatschenko2, Klaus Richter2, Dieter Weiss1, and Jonathan Eroms1 — 1Institut für Experimentelle und Angewandte Physik Universität Regensburg, 93053 Regensburg — 2Institut für Theoretische Physik Universität Regensburg, 93053 Regensburg — 3National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
We report on ballistic transport in graphene-boron nitride heterostructures with a tunable charge carrier density profile. Employing a dry van-der-Waals stacking method, we prepare high mobility graphene devices, where the charge carrier mean free path can exceed the lattice period of the induced multibarrier system by several times. These potential barriers are generated by multiple local top gate electrodes and a global back gate, and yield a pronounced Fabry-Pérot interference pattern in the bipolar transport regime. The extended ballistic length - in comparison to former samples - gets us within reach of the superlattice effect, which we highlight by matching the experimental data to a model calculation. We additionally apply a high, perpendicular magnetic field to our multibarrier systems and observe mode-mixing in the Quantum-Hall-regime of a 4-point measurement setup. By comparing samples with different top gate periods and separately controllable top electrodes, we study adiabatic and equilibrated unipolar edge channel transmission and suppression of equilibration at bipolar junctions.