Nanoscale CVD Graphene Hall Probes for high resolution Scanning Probe Microscopy

Advances in magnetic imaging are one of many improvements in instrumentation which have enabled scientists to pioneer and develop their next big research ideas. One important technique, scanning Hall probe microscopy (SHPM), involves rastering a Hall sensor over a surface to create a magnetic field map across the sample. However, SHPM has typically relied on the low temperature performance of GaAs-based Hall probes, whose figures-of-merit become much worse at room temperature. This tends to exclude SHPM from numerous applications under ambient conditions such as susceptometry for non-destructive evaluation and characterisation of ferromagnetic data storage media. Making use of graphene's high carrier mobility and facile CVD growth techniques, we have fabricated graphene Hall devices with nanoscale lateral dimensions for sub-100nm spatial resolution imaging while maintaining excellent room temperature minimum detectable fields in the μT/√Hz range. We will illustrate the imaging performance of such probes, including; low frequency noise performance and magnetic sensitivity, for devices with different active areas, carrier densities and drive currents.
*Funding was provided by the Lloyds Register Foundation and the UK EPSRC, with award numbers G0086 and EP/R007160/1 repesctivley.