<p>Quantum Hall effect (QHE) in graphene has been widely studied due to its simple device architecture, modest cryogenic requirements, and the unique non-equidistant Landau-level spectrum of Dirac carriers. Real-space visualization of the QHE in graphene is essential both for elucidating fundamental physics and for guiding graphene-based device design. Here, we present a novel scanning approach termed parallel EFM-sMIM imaging (PEMI) mode, which combines electrostatic force microscopy (EFM) and scanning microwave impedance microscopy (sMIM) to investigate the spatially distributed QHE in graphene. Comparative analysis reveals that the single-pass EFM mode demonstrates superior spatial resolution and signal-to-noise ratio compared to the constant-height EFM mode. PEMI measurements reveal that graphene’s electrical conductance manifests as discrete island-like domains exhibiting remarkable stability against magnetic field variations, and spatially distributed QHE states demonstrate independent emergence and evolution within these conductance islands. Notably, while tip-bias compensation demonstrates effectiveness in mitigating crosstalk interference, this technique inherently presents a trade-off by compromising the resolution of EFM signals. Finally, we employ contact-mode sMIM to measure carrier density and determine carrier type. This framework establishes a novel paradigm for parallel characterization of QHE textures and demonstrates promising extensibility to diverse 2D electronic systems through its adaptable architecture.</p>

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Synchronous multi-technique scanning mode for probing spatially distributed quantum Hall effect in graphene

  • Runnong Zhou,
  • Shiyu Zhu,
  • Jiawei Hu,
  • Jianfeng Guo,
  • Zhang Zhou,
  • Yunhao Wang,
  • Zhihai Cheng,
  • Chengmin Shen,
  • Haitao Yang,
  • Hong-Jun Gao

摘要

Quantum Hall effect (QHE) in graphene has been widely studied due to its simple device architecture, modest cryogenic requirements, and the unique non-equidistant Landau-level spectrum of Dirac carriers. Real-space visualization of the QHE in graphene is essential both for elucidating fundamental physics and for guiding graphene-based device design. Here, we present a novel scanning approach termed parallel EFM-sMIM imaging (PEMI) mode, which combines electrostatic force microscopy (EFM) and scanning microwave impedance microscopy (sMIM) to investigate the spatially distributed QHE in graphene. Comparative analysis reveals that the single-pass EFM mode demonstrates superior spatial resolution and signal-to-noise ratio compared to the constant-height EFM mode. PEMI measurements reveal that graphene’s electrical conductance manifests as discrete island-like domains exhibiting remarkable stability against magnetic field variations, and spatially distributed QHE states demonstrate independent emergence and evolution within these conductance islands. Notably, while tip-bias compensation demonstrates effectiveness in mitigating crosstalk interference, this technique inherently presents a trade-off by compromising the resolution of EFM signals. Finally, we employ contact-mode sMIM to measure carrier density and determine carrier type. This framework establishes a novel paradigm for parallel characterization of QHE textures and demonstrates promising extensibility to diverse 2D electronic systems through its adaptable architecture.