What is demagnetization?

Demagnetization is when a magnet loses all magnetism, ceasing to have its properties and to be a magnet.

What is the demagnetization of a magnet?

In the context of the term, we speak of a process when the magnetic field of a permanent magnet or a ferritic to become permanent magnet material disappears totally or partially. For example, this procedure is intended for tools so that the tool used does not attract shavings or other ferrous materials.


What happens during demagnetization?


In an externally applied magnetic field, ferromagnetic materials become a magnet. Other materials such as para and diamonds can be magnetized. In these materials, however, the magnetization is much weaker. The magnetic forces disappear in para and diamagnetos when the external magnetic field is eliminated. However, the so-called remanence in ferromagnets ensures that even if the external magnetic field is eliminated, a residual magnetization remains. The residual magnetic force cannot disappear by itself without external circumstances.

If you want to understand that, you need a ferromagnetic material (iron) and a strong magnet. The ferromagnetic material fits this magnet. For example, you can take a pair of scissors. Approach the magnet of the scissors and remove the magnet again. After removing the magnet, the scissors become slightly magnetic. With the pair of scissors you can now place light iron items such as nails. If you want the magnetic forces in the scissors to disappear, hit the scissors against  a  strong  resistance.  Due  to  mechanical  stress,  the  scissors  are  demagnetized.


In each atomic element of para and ferromagnets, electron spin magnetic moments physically dominate. These pairs behave like the smallest elementary magnets of a matter. In ferromagnets there is an additional exchange interaction. This is a strong interaction between the electron gyres, which also stabilizes them. The exchange interaction improves the parallel alignment of the electronic rotation as soon as ferromagnetic materials are magnetized by a magnet.


The mixing of the already aligned electron spins is normally prevented by this exchange interaction and thus the loss of magnetic forces. After this process, the magnetic forces of a magnet are zero. If the magnet has not been completely destroyed, re-magnetisation may occur.


Influences on demagnetization.

Magnetic fields can be different in external violence, for example, by hard blows on the magnet. Of course, this also applies to other strong mechanical stresses suffered by a magnet. A strong vibration    changes    the    structure    of    the    spines    of     the     aligned     electrons.     Even strong thermal loads can eliminate the magnetic field. The kinetic energy of electrons increases with increasing temperature. The high kinetic energy of the electrons destabilizes the spin structure of the aligned electron. The maximum allowable temperature of a material in which the structure is changed so much that the magnet is demagnetized is called the Curie temperature.

Another case in which a magnetic field can be destroyed is through another very strong magnetic field. Here, the externally applied magnetic field must be opposite to the direction of the elementary magnet (the rotation of the aligned electron). Ferromagnets are destroyed when an external magnetic field of opposite magnetic direction and a certain maximum field strength, called coercive force, approaches the ferromagnetic field.

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