Probing charging and localization in the quantum Hall regime by graphene $p--n--p$ junctions

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Probing charging and localization in the quantum Hall regime by graphene $p - n - p$ junctions

Jairo Velasco, Jr., Gang Liu (刘钢), Lei Jing (荆雷), Philip Kratz, Hang Zhang (张航), Wenzhong Bao (包文中), Marc Bockrath, and Chun Ning Lau (劉津寧)

Phys. Rev. B 81, 121407(R) – Published 9 March 2010

Abstract

Using high-quality graphene $p n p$ junctions, we observe prominent conductance fluctuations on transitions between quantum Hall (QH) plateaus as the top gate voltage $V_{t g}$ is varied. In the $V_{t g} − B$ 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.