erromagnetIC: in ferromagnetic materialS, such as iron, the magnetization can be much larger than that ot para-or diamagnetIc substances Domain: in ferromagnetic materials there are re gions in which electron spins are aligned. The mag netization of one domain may be oriented at random w.r.t. that of a neighboring domain Remark: usually dielectric D O E, linear; but in ferromagnetic materials the magnetization is non linear and depends on history