Imaging backscattering through impurity-induced antidots in quantum Hall constrictions

Nicola Paradiso, Stefan Heun, Stefano Roddaro, Giorgio Biasiol, Lucia Sorba, Davide Venturelli, Fabio Taddei, Vittorio Giovannetti, Fabio Beltram

Published 2012-09-11Version 1

We exploit the biased tip of a scanning gate microscope (SGM) to induce a controlled backscattering between counter-propagating edge channels in a wide constriction in the quantum Hall regime. We compare our detailed conductance maps with a numerical percolation model and demonstrate that conductance fluctuations observed in these devices as a function of the gate voltage originate from backscattering events mediated by localized states pinned by potential fluctuations. Our imaging technique allows us to identify the necessary conditions for the activation of these backscattering processes and also to reconstruct the constriction confinement potential profile and the underlying disorder.