Work

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

Year: 2025

Type: article

Abstract: 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.

Source: Quantum Frontiers

DOI: 10.1007/s44214-025-00089-1