LXX. Some magnetic properties of dilute ferromagnetic alloys : I

Summary The theory of the coercivity of non-spherical, single domain particles of ferromagnetic material in a non-magnetic matrix has been developed independently by Néel (1947) and Stoner and Wohlfarth (1948). Appropriate conditions for the study of the growth of these domains are to be found in suitable dilute ferromagnetic alloys where there is an increase of solubility of the ferromagnetic constituent with temperature. Such characteristics are found in the copper rich alloys of copper-cobalt and copper-iron. The magnetic properties of appropriate alloys with increase of heat treatment are followed from the normal paramagnetism of the solid solution to the ordinary magnetization curve of the precipitated ferromagnetic. At a suitable stage a maximum in the coercivity is found which the writers believe to be associated with single domain precipitates. The characteristics of the hysteresis loops at this stage indicate the presence of high coercivities of more than 1000 oe.