We all are familiar with the word magnet and so with the term magnetic materials. In general, it is known that every matter is magnetic.
Basically, every element in the universe possesses some magnetic behaviour as their composition involves charged particles i.e., proton and electron. However, the degree of possessing magnetism differs from one to another.
The arrangement of the charges in the atomic structure of the material is responsible for the magnetic property exhibited by them.
Generally, all those materials that experience an attractive force when placed near magnets are known as magnetic materials.
Here, in this article, we will see the categories in which magnetic materials are categorized.
Magnetic Classification of Materials
The various classifications of magnetic materials are done on the basis of the response provided by these materials when present near a magnetic field.
This depends on the level of interaction present between atomic magnetic moments. As sometimes the interaction is almost negligible while sometimes it is quite strong.
Hence, these are classified as:
Diamagnetic materials are the type of materials that are less magnetized in the presence of an external magnetic field but in the opposite direction to that of the applied field. The compounds in which the atomic structure has completely filled shells possess diamagnetic behaviour.
The charges in these metals manage to partially shield the nucleus from the external field. These materials offer small susceptibility with negative polarity.
Example: Noble gas and various metals and non-metals like silver, gold, argon, boron, etc.
These materials are weakly magnetized by the externally applied magnetic field but in the same direction of the supplied field. Here the orientation of the magnetic moment is in the same direction of the applied field. It exhibits permanent magnetic moment due to the motion of electrons in its orbit and spin motion along the axis.
When the external field is provided then the magnetic moment is aligned in the direction of the field. Thereby providing a large amount of magnetization. But the temperature variation only allows partial alignment thus resulting in weak magnetization.
It exhibits positive susceptibility.
Example: Aluminium, Calcium, Potassium, Lithium, etc.
It is referred to as a subgroup of paramagnetic materials. These materials possess a strong magnetic field. Here each atom in the molecular structure exhibits a permanent magnetic moment.
With the application of an external magnetic field, the magnetic moment gets aligned along the direction of the field. Thereby giving rise to a natural magnetization.
Here the susceptibility is positive and quite large.
It exhibits hysteresis, which means even after the removal of the magnetic field, magnetization is retained.
Example: Cobalt, Iron, nickel and their alloys.
In these materials, there exists strong but negative interaction between the sub-lattices of the structure thus there is an antiparallel arrangement.
This gives rise to the spontaneous magnetic field. So, the materials that possess a spontaneous magnetic field on applying an external magnetic field are known as ferrimagnetic.
Example: Compounds of iron oxide with oxides of rare earth.
The materials exhibiting almost negligible magnetism in the presence of an external magnetic field are antiferromagnetic in nature.
In these materials, the adjacent ions align themselves in the opposite orientation. Thus, the magnetism of the ions in one direction gets cancelled out by the ions possessing reverse alignment. This antiparallel coupling is destroyed with an increase in temperature.
Example: Manganese monoxide, iron oxide, nickel oxide, iron chloride, etc.
Hence in this way, the various magnetic materials are classified.