Using high quality graphene pnp junctions, we observe prominent conductance fluctuations on transitions between quantum Hall (QH) plateaus as the top gate voltage Vtg is varied. In the Vtg-B plane, the fluctuations form crisscrossing lines that are parallel to those of the adjacent plateaus, with different temperature dependences for the conductance peaks and valleys. These fluctuations arise from Coulomb-induced charging of electron- or hole-doped localized states when the device bulk is delocalized, underscoring the importance of electronic interactions in graphene in the QH regime.
@article{arxiv.0912.3179,
title = {Probing Charging and Localization in the Quantum Hall Regime by Graphene pnp Junctions},
author = {Jairo Velasco and Gang Liu and Lei Jing and Philip Kratz and Wenzhong Bao and Marc Bockrath and Chun Ning Lau},
journal= {arXiv preprint arXiv:0912.3179},
year = {2015}
}