Graphene-based Hall probe magnetic imaging*

Hall probe microscopy is a powerful tool for mapping magnetic fields across a sample surface, and can be used to investigate key properties of magnetic and superconducting materials. However, to date the technique has not been widely used under ambient conditions because the figures-of-merit of available GaAs-based Hall probes degrade substantially at room temperature. To address this we have recently demonstrated sub-100nm CVD graphene Hall devices with room temperature field resolutions in the μT/√Hz range, greatly exceeding the performance of GaAs-based Hall probes.¹ Additionally, we have demonstrated improved stability and increased mobility in graphene devices encapsulated in HSQ.² We build upon these developments to optimise CVD graphene Hall probes for high resolution ambient magnetic imaging. We also report progress made in extending the technique to include local susceptometry mapping for, e.g., characterisation of ferromagnetic data storage media.
1. D. Collomb et. al., Sci. Rep., 9(1), 1-10 (2019)
2. P. Li et. al., Mater. Lett., 257, 126765 (2019)