ULTRAHIGH-RESOLUTION MAGNETIC FORCE MICROSCOPE TIP FABRICATED USING ELECTRON-BEAM LITHOGRAPHY

A novel magnetic force microscope tip has been proposed and fabricated that consists of a approximately 30 nm thick ferromagnetic film coated on one side of a nonmagnetic pillar which is approximately 150 nm wide and over 1.5 mum long. The pillar was fabricated on the apex of a commercial scanning force microscope tip using high-resolution electron beam lithography. The ferromagnetic film was evaporated on the pillar from an angle so that only the pillar, not the rest of the tip, was coated. The coated ferromagnetic film has a trough shape and a tapered end with a tip radius of approximately 10 nm. The film is single domain because of the nanoscale size and shape anisotropy. Compared to conventional Ni wire tips, the new tips have a much smaller, magnetic cross section at the end of the tip, thus offering better imaging resolution and they have lower stray field, thus making them well suited to measuring soft magnetic materials.