Single Domain Fine Particles
Magnetic properties depend not only on the crystal structure of the particle but on the shape because different shapes give rise to different external magnetic fields.
An elongated fine particle has its magnetization along its length...
Made by compacting barium ferrite or strontium ferrite... used for many low cost applications
Rare earth cobalt
based on samarium - cobalt alloys... used in DC motors, stepper and servo motors, traveling wave tubes, klystrons, and gyroscopes.