A magnet (permanent magnet), which totally or partially retains its magnetism after previous magnetization. Present-day permanent magnetic materials are many times superior in their coercive field force, and therefore more stable than magnets of a few decades ago.
Anisotropy:
This means, that certain physical quantities have different values according to direction. Foranisotropic hard magnets, the magnetic powder is aligned in an intense magnetic field during compression. Higher magnetic values result in the direction of this magnetic field than in the transverse direction.
Demagnetizing curve:
The part of the hysteresis cycle which runs in the second quadrant of a rectangular system of coordinates.(see A) The course of the demagnetization curve and its final values Br (remanence) and Hc (intensity of the coercive field) characterize the essential magnetic properties of a permanent magnet
Remanence:
Br is indicated in (T) or (Gs). Remaining magnetization in magnetic material, which has been magnetized up to saturation point, in a closed circuit. Apparent remanence refers to have the value which results from a partially open magnetic circuit.
Coercive field force:
The unit of coercive field force is indicated by A/m or Oe. It is the field force Hc, which causes the magnetization of ferro-magnetic material, which had previously been magnetized up to saturation point, to revert to zero.
