Particle media: They have greated magnetic coercivity and a thinner magnetic layer than that of conventional 3,5" microdisks. ... In relation to the particle media, it is argued that the many and continuing improvements which have been made to the microdisk in terms of memory and speed are all based on continuing refinements of the two key elements of the size and shape of the magnetic particles in the magnetic layer, and on the thickness of the magnetic layer.
