Using electron beam nanolithography and electroplating, arrays of Ni pillars on silicon that have a uniform diameter of 35 nm, a height of 120 nm, and a period of 100 nm were fabricated. The density of the pillar arrays is 65 Gbits/in.2-over two orders of magnitude greater than the state-of-the-art magnetic storage density. Because of their nanoscale size, shape anisotropy, and separation from each other, each Ni pillar is single domain with only two quantized perpendicular magnetization states: up and down. Each pillar can be used to store one bit of information, therefore such nanomagnetic pillar array storage offers a rather different paradigm than the conventional storage method. A quantum magnetic disk scheme that is based on uniformly embedding single-domain magnetic structures in a nonmagnetic disk is proposed.
Isolated nanoscale Ni bars with a length of 1 pm, a width from 15 to 300 nm, and interactive bar arrays with a spacing from 200 to 600 nm were fabricated using electron-beam lithography and were studied using magnetic force microscopy. The study showed that the virgin magnetic state of bars with a width smaller than 150 nm was single domain and otherwise multidomain. It also showed that the switching field of isolated bars initially increases with decreasing bar width, then reaches a maximum switching field of 740 Oe at a width of 55 nm? and afterwards decreases with further bar width reduction. Furthermore, it was found that the switching field of the interactive bars decreases almost linearly with reduction of the spacing between the bars.
Abstruct -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 pm 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.
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