1963 Guthrie lecture: Magnetic processes in weak and moderate fields

A survey, based on the domain concept, is given of the outstanding features of the magnetic processes which may play a part when a ferromagnetic material, in particular iron or silicon-iron, is exposed to fields of weak or moderate intensity. The effects of closure domain configurations on the shape of the hysteresis loop and the effects of domain nucleation and growth in determining the magnetic properties of a material are discussed, both qualitatively and quantitatively, in the light of the results of Bitter figure and magnetothermal experiments; and the importance of the results to a proper understanding of basic magnetic phenomena, such as coercivity is discussed.