Particulate magnetic recording media

High density magnetic recording is experiencing rapid technological growth with the merging of the data recording and the audio-visual professional and consumer applications into all digital formats. Media evolution has been following a path from oxide particles to metal particles and ultimately to metal thin films which could provide the highest magnetization and the smallest thickness. Recent developments of very small metal and barium ferrite particles, coupled with double-coating technology which allows the coating of very thin and smooth particulate magnetic layers, combine to produce advanced particulate media which outperform metal film media, while also providing higher reliability and lower cost. Micromagnetic and other theoretical simulations show that high magnetization is undesirable at short wavelengths because of demagnetization and the spreading of the transition regions. Barium ferrite particulate coatings have low demagnetization, can support very narrow transitions, can be easily extended to perpendicular recording, and are completely immune to environmental and chemical corrosion, making them the best choice for high density recording at multi-Gbit/in(2) areal densities, particularly in combination with high sensitivity MR and GMR transducers.