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.
@article{arxiv.1009.1713,
title = {Transmission coefficient through a saddle-point electrostatic potential for graphene in the quantum Hall regime},
author = {Martina Flöser and Thierry Champel and Serge Florens},
journal= {arXiv preprint arXiv:1009.1713},
year = {2010}
}
Comments
4 pages, 2 figures Minor modifications as published