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What exactly is remanence?

When we speak of remanence, it is the magnetization in which an iron nucleus is attached under the influence of an external magnetic field. Therefore, it is also called residual magnetism. 

This phenomenon can be measured by magnetic flux density. But let's start from the beginning to explain the whole concept.

Ferromagnetic materials, such as an iron core, are magnetizable materials consisting of elementary magnets inside. These particles are also called spin or electron spin. These are units have a magnetic dipole of fixed magnetic size and have a variable direction. They are units that can point in different directions, which makes the iron core appear non-magnetic.

If an external magnetic field is applied to the iron core, the elemental magnets move within it and adapt to the structure of the external magnetic field. This means that they are aligned in a certain direction and therefore form a total magnetic field around the iron core. Even if we eliminate the external magnetic field, the iron core remains magnetized. This magnetization is called remanence.

It can also be measured. The corresponding numerical value shows us how strong the resulting magnetization is and is measured in the remnant flux density, and is given as a unit in Gauss or Tesla.

What makes ferromagnetic materials so special is the fact that they show a particularly strong remanence when the external magnetic field is removed.

The elements with ferromagnetic properties are the following:

-At room temperature:

  • Iron
  • Nickel
  • Cobalt
  • Ruthenium

 

-At lower temperatures:

  • Lanthanides
  • Gadoliunium
  • Terbium
  • Dysprosium
  • Holmium
  • Erbio

 

The influence of temperature on the remanence of a substance.

Temperature also plays an important role in the remanence of a material. It's related to electron spins. As already mentioned, they are in constant motion and align as soon as an external magnetic field is applied. However, the higher the temperature, the more the movement of these turns increases, which in extreme cases can cancel the magnetization. Therefore, it is important to always observe the operating temperatures of the different magnets.

In addition to the operating temperature, the degree of hardness of the magnetic material must also be taken into account. For soft magnetic materials, the remanence is lower, i.e. the magnetization does not last long when the external magnetic field is removed. The opposite is the case with hard magnetic materials.

The arrangement of the electron rotations can also be changed by vibrations, which also influences the remanence.

As you can see, it is important to consider all of these factors before deciding on a magnet for your application. Therefore, we recommend that you simply contact our technical staff. We are happy to provide you with information and are available for all your questions.

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