Graphene Hall Sensors for Measuring and Mapping Earth's Magnetic Field

In this work, we study Hall transport in bilayer graphene encapsulated in thin hBN, with a focus on measuring and mapping the Earth's magnetic field. Device design is optimized using key Hall sensor parameters including sheet resistivity, cross geometry, field strength and orientation, and readout bandwidth set by the lock-in frequency. Rotation of the probe provides vector sensitivity: as the device is tilted, it measures the component of the ambient magnetic field normal to the graphene plane. This built-in rotational degree of freedom enables spatial mapping of the Earth's magnetic field.

This platform can also be adapted for sensitive magnetic detection in condensed matter systems, chemical environments, and biological systems, offering a path toward compact room-temperature field sensing across multiple domains.