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arXiv · 2201.06934

Imaging of sub-$\mu$A currents in bilayer graphene using a scanning diamond magnetometer

M. L. Palm·W. S. Huxter·P. Welter·S. Ernst·P. J. Scheidegger·S. Diesch·K. Chang·P. Rickhaus·T. Taniguchi·K. Wantanabe·K. Ensslin·C. L. Degen
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Abstract

Nanoscale electronic transport gives rise to a number of intriguing physical phenomena that are accompanied by distinct spatial patterns of current flow. Here, we report on sensitive magnetic imaging of two-dimensional current distributions in bilayer graphene at room temperature. By combining dynamical modulation of the source-drain current with ac quantum sensing of a nitrogen-vacancy center in a diamond probe, we acquire magnetic field and current density maps with excellent sensitivities of 4.6 nT and 20 nA/$\mu$m, respectively. The spatial resolution is 50-100 nm. We further introduce a set of methods for increasing the technique's dynamic range and for mitigating undesired back-action of magnetometry operation on the electronic transport. Current density maps reveal local variations in the flow pattern and global tuning of current flow via the back-gate potential. No signatures of hydrodynamic transport are observed. Our experiments demonstrate the feasibility for imaging subtle features of nanoscale transport in two-dimensional materials and conductors.

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M. L. Palm, W. S. Huxter, P. Welter, S. Ernst, P. J. Scheidegger, S. Diesch, K. Chang, P. Rickhaus, T. Taniguchi, K. Wantanabe, K. Ensslin, C. L. Degen. 2022-01-18. Imaging of sub-$\mu$A currents in bilayer graphene using a scanning diamond magnetometer. https://doi.org/10.1103/physrevapplied.17.054008

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