b）

Figure: 3-8 a) A simple picture suggesting the origin of electron spin movement; b) relating the

magnetic moment induced in an electron cloud by a change in magnetic field

Figure: 3-9 Relating the magnetic moment to a simple electron orbit.

The details are obviously more complex but this provides a simple pictorial model to use.Atoms are formed of elec-trons and protons plus neutrons. The electrically changed components have intrinsic and orbital spin when they form molecules of a given type of material. The particular orientation of the spin axes of the individual particles can be aligned in random or structured ways and may be altered by an ambient magnetic field. If the molecular structure does not accept random spin orientation but requires a structured crystalline architecture, the material

can have a per-manent magnetization. If component parts can move to align parallel