Hall nano-probes fabricated by focused ion beam

Hall magnetometers with active areas down to 100 × 100 nm2 were fabricated patterning gold and Si-doped GaAs films by focused ion beam. For GaAs probes, electrical characterization shows that the magnetic flux sensitivity is better than 10-2?0 at room temperature. Hall nano-probes made of gold can work down to liquid helium temperature with magnetic flux sensitivity 10-1?0.