An experimental investigation of magnetization reversal in advanced metal particles

The basic processes of magnetization in metal particles for advanced record ing technology, with high coercivity and saturation magnetization, are expe rimentally investigated. The study is carried out through the experimental analysis of the rotational hysteresis, the measurement of angular dependenc e of the coercive field, the evaluation of the magnetic anisotropy and of i ts distribution and the determination of the thermal activation volume, as deduced from the variation of the magnetization with time, in correlation w ith the results of the particle structure analysis. The analysis indicates that the magnetization reversal of the whole particle is incoherent, or not cooperative, but that coherent rotation can take place in the crystallites composing the particle itself.