An ultra-high resolution single-domain magnetic force microscope tip fabricated using nanolithography

An ultra-high resolution MFM tip is proposed and demonstrated. The tip consists of a ~30 nm thick ferromagnetic film coated on a non-magnetic pillar that has a diameter of 150 nm, a length over 1.5 μm and a sharp end of a 10 nm radius. The pillar was fabricated on the apex of a commercial scanning force microscope tip using electron beam lithography. The ferromagnetic films were coated only on one side of the pillar but not on the rest of the tip. Therefore, the tip has a trough shape and a tapered end with a tip radius of ~10 nm. The ferromagnetic trough is single-domain because of its nanoscale size and shape anisotropy. Compared to conventional Ni wire tips, the new tips have a much smaller magnetic charge distribution at the end of the tip, thus offering better imaging resolution. Furthermore, they have a lower stray field, thus making them well suited to measuring soft magnetic materials