The mechanism in physics using which some materials strongly attract each other is known as ferromagnetism. These materials usually include iron, lodestone, and other similar things. It is an important phenomenon of nature that is the cause of magnetism in materials. 

Ferromagnetism is an essential phenomenon and ferromagnetic materials are widely used in various industries. These industries are the ones that produce and manufacture generators, electric motors, transformers, etc. In these ‘Causes of ferromagnetism’ notes, you will learn in detail about the characteristics of ferromagnetism and most importantly, the causes of ferromagnetism.

What are some of the naturally occurring ferromagnets?

Ferromagnets are also present in the world around us naturally. Some of the naturally occurring ferromagnets are iron, lodestone, compounds which include iron, cobalt, nickel, etc. These materials exhibit ferromagnetic properties and greatly influence and cause the entire phenomenon of magnetism. Some of the materials which occur rarely as ferromagnets are gadolinium and some other rare earth metals. 

What are the causes of ferromagnetism?

There are various reasons for the phenomenon of ferromagnetism. Some of them are :

• One of the major causes of ferromagnetism is the net angular momentum in the ferromagnets. Now, this angular momentum in the ferromagnets can be caused either through the spin component or the orbital component. In other words, we can say that the net angular momentum which affects the ferromagnetism properties of the ferromagnets is the rotational analog of linear momentum.
• Another of the chief causes of ferromagnetism is that the electrons in the atoms spin. The spinning of the electrons of the atoms is one of the major causes of ferromagnetism. By the spinning of electrons, it means that the electrons rotate or spin around their own axis. There is a particular speed with which they spin. The conclusion which can be derived is that the spinning of electrons makes the materials gain ferromagnetic properties.
• The magnetization also depends on the intensity of the respective magnetic field. The materials get magnetised when subjected to a magnetic field with good magnetic strength. This magnetization has such a strong effect that the magnetic properties are retained by the ferromagnetic materials even after the magnetic field has been removed.
• Ease of alteration of dipoles is another of the causes of ferromagnetism. Alteration of dipoles is necessary for being magnetised of a material. If a material is easily getting its dipoles altered, it means that it can be a good ferromagnetic material. Thus, we can say that ease in the alteration of dipoles is another of the chief causes of ferromagnetism.

Why is ferromagnetism important?

Ferromagnetism is a physical phenomenon that has a great importance for its usage in different industries for various things. The ferromagnets are used in the core of the transformers in the electric departments. It can convert a material that can be converted into a magnet into a permanent magnet. Besides this, the ferromagnetic materials have their use in dynamo and motor. By following the process of magnetic induction, one can convert an iron object or any object which can be changed into a magnet into a permanent magnet. 

Learned about the causes of ferromagnetism? Now, let’s have a look at some of the characteristics of the ferromagnets –

• The relative magnetic permeability of the ferromagnets is very high and of the order 102 to 106.
• They are very strongly attracted to magnets.
• Hysteresis property is exhibited by the ferromagnetic materials.
• When the ferromagnets are placed in an external magnetic field, the magnetic field lines become denser inside the material.
• The magnetic susceptibility for them is much greater than unity.
• The ferromagnets are permanent magnets. This is because they are able to retain the magnetic properties even after the magnetic field has been removed from their vicinity.
• The ferromagnetic materials after crossing the threshold of Curie temperature, become and behave like paramagnetic materials. The paramagnetic materials are the ones that are not very strongly attracted to a magnetic field.

What is antiferromagnetism?

The antiferromagnets are the magnets that have antiparallel magnetic moments, unlike the ferromagnets which have parallel magnetic moments. Some examples of ferromagnets are nickel oxide, chromium, and manganese fluoride.

Although it is an interesting thing, it is not of much significance as the ferromagnets in the laboratories and other industries.

Rare ferromagnetic materials

Besides just the metals, some other materials are also found to be ferromagnetic in nature. In these ‘causes of ferromagnetism notes’ we will learn about them. At room temperature, many of the actinide compounds behave as ferromagnets. Some materials can also be made ferromagnets by electrically being induced. 

Conclusion

Ferromagnetism is the phenomenon of the materials (like iron and some other elements and compounds) attracting each other strongly. It is a physical phenomenon of vital importance in many physical and chemical industries. Ferromagnets have various uses in many fields. They are usually used in the core of the transformers and also in the magnetic tape recordings. Some rare materials which are not ferromagnets under normal conditions can be made into ferromagnets. This can be done by subjecting them to the favourable conditions for that- be it, a lower temperature or electrically inducing them. They are greatly supporting many industries with their existence and are of great importance.