NOVEL MODE OF MAGNETIZATION REVERSAL IN 'TAPE' PARTICLES.

The underlying theme of the work on 'tape' particles at PRL, has been to attain an understanding if the bulk magnetic properties of a recording tape by a process of synthesis, that is to first measure and account for the properties of individual acicular 'tape' particles, and then to examine theoretically the magnetic properties of tapes made from them. Methods were devised to measure the hysteresis loop and anisotropy field of an individual particle, which is a cigar-shaped body approximately 0. 5 mu m long. It was found that for gamma -Fe//2O//3, the proposed 'flipping' model of reversal accounted for a number of experimental observations, for which the existing four models did not give a satisfactory explanation. It underlines the possible importance of the shapes of the ends of the particles.