Scanned Potential Microscopy of Edge and Bulk Currents in the Quantum Hall Regime

TL;DR

This study employs atomic force microscopy to map local voltages in a 2D electron gas within the quantum Hall regime, revealing distinct profiles at edges and bulk that elucidate current distribution.

Contribution

It provides direct local measurements of voltage profiles in the quantum Hall regime, offering new insights into edge and bulk current behaviors.

Findings

Linear voltage profile in bulk during transition regions

Nonlinear voltage profile on QH plateaus

Localized voltage drops at sample edges

Abstract

Using an atomic force microscope as a local voltmeter, we measure the Hall voltage profile in a 2D electron gas in the quantum Hall (QH) regime. We observe a linear profile in the bulk of the sample in the transition regions between QH plateaus and a distinctly nonlinear profile on the plateaus. In addition, localized voltage drops are observed at the sample edges in the transition regions. We interpret these results in terms of theories of edge and bulk currents in the QH regime.