ABSTRACT
The spin magnetic moments within a ferromagnetic material interact with each other even when there is no external field present by a quantum mechanical exchange coupling force. These interactions cause the creation of a strong internal molecular magnetic field. This field causes neighbouring moments to align themselves parallel to each other in regions called magnetic domains of size approximately 107m. With no external field, the orientations of the domains are random. Within a domain, the orientation of the magnetic moments is aligned and the magnetisation is at the saturation level. When an external field H is applied, the domains tend to reorient so that the effect of this is that those d i l d i li t ith th fi ld t d t i i t th
oma ns a rea y n a gnmen w e e en o grow n s ze a e expense of others, not aligned, which shrink. As H is increased, a saturation point is reached where all domains contain magnetic moments that are aligned with the field.
