Transmission coefficient through a saddle-point electrostatic potential for graphene in the quantum Hall regime

Abstract

From the scattering of semicoherent-state wavepackets at high magnetic field, we derive analytically the transmission coefficient of electrons in graphene in the quantum Hall regime through a smooth constriction described by a quadratic saddle-point electrostatic potential. We find anomalous half-quantized conductance steps that are rounded by a backscattering amplitude related to the curvature of the potential. Furthermore, the conductance in graphene breaks particle-hole symmetry in cases where the saddle-point potential is itself asymmetric in space. These results have implications both for the interpretation of split-gate transport experiments, and for the derivation of quantum percolation models for graphene.

arXiv comment4 pages, 2 figures Minor modifications as published

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• Low Magnetic Field Regime of a Gate-Defined Constriction in High-Mobility Graphene
• Spontaneous localization at a potential saddle point from edge state reconstruction in a quantum Hall point contact