Perpendicular recording on magnetic particles using probe heads

A study has been made of perpendicular recording onto arrays of magnetic particles, with one data bit per particle, using probe heads. Two types of head have been considered, shielded and unshielded, and their field distributions derived. Recording onto magnetically anisotropic particles reversing their magnetizations by coherent rotation processes, and onto particles undergoing magnetization reversal by incoherent rotation has been investigated. The latter is shown to lead to higher information storage densities and the use of shielded heads is most favourable.