an attractive or repulsive field. Objects that get attracted by a magnet are called magnetic materials.
Again, not all materials are naturally magnetic. There are certain types of material that require special modifications. At the same time, there are some that are non-magnetic materials.
Here are some common magnetic materials:
Types of Magnetism
1. Paramagnetism
Paramagnetism is a form of magnetism that is feebly attracted to an externally created magnetic field. Such kind of magnetism can only be exhibited by paramagnetic materials. Paramagnetic materials are made of permanent atomic dipoles running parallelly in the same direction as the external field.
When the external magnetic field is removed, paramagnetic materials lose their magnetic properties. However, the unpaired electrons will still exist. Due to their low positive susceptibility, paramagnetic materials are attracted by other magnets but they cannot attract other paramagnet materials.
Another characteristic of paramagnetism is that it is temperature-sensitive. An increase in temperature decreases the magnetic moments of its atoms.
You can only tell if a magnetic material is paramagnetic or not by looking at its electronic configuration. A paramagnetic material has unpaired electrons (an odd number of electrons). Some examples of materials that exhibit paramagnetism include titanium, oxygen, aluminum, etc.
2. Ferromagnetism
Ferromagnetism is a form of magnetism in which the magnetic material attracts or is attracted strongly by other magnetic materials. A ferromagnetic material gets magnetized when exposed to an external magnetic field. In stronger magnetic fields, ferromagnetic materials can be magnetized to the saturation limit.
Removal of an external magnetic field does not take away their ferromagnetic properties. Ferromagnetic materials are also sensitive to temperatures beyond their curie point. Past this point, they lose their magnetism. However, on cooling, they regain their magnetic properties.
The number of atoms ions in a ferromagnetic material even creates a magnetic field from within the material. Therefore, ferromagnetic materials have lasting magnetic moments. Some examples of ferromagnetic materials include; cobalt, nickel, iron, and some of their alloys.
3. Antiferromagnetism
Antiferromagnetism is a form of magnetism in which the atoms within a material are arranged uniformly but moving in the opposite direction from the adjacent atoms. Antiferromagnetic materials have unique qualities that can be used in applications like data storage, sensors, and spintronics.
When antiferromagnetic materials are exposed to temperatures below the Neel point, they lose their antiferromagnetic properties. They become paramagnetic materials.
Some examples of antiferromagnetic materials include; iron oxide, manganese oxide, chromium, copper (II) oxide, and nickel (II) oxide.
4. Ferrimagnetism
There are magnetic material with:
- Can attract other magnets
- External magnetic fields can also attract these materials
Ideally, these are unique magnetic materials that experience both ferromagnetic properties and antiferromagnetic properties. Moreover, on exposure to extremely high temperature (above curie temperature), they will lose the external magnetic properties.
They regain their ferrimagnetism on cooling, making them permanently magnetic.
Generally, ferrimagnetism mainly occurs in ferrites (a type of magnetic oxide). Some examples of ferrimagnetic materials are yttrium iron garnet, trevorite, magnesioferrite, and magnetite.
5. Diamagnetism
Diamagnetism is an occurrence in which some materials when exposed to an external magnetic field, tend to move away from the field. Naturally, all materials are diamagnetic. However, some materials have stronger magnetic properties that are stronger than their diamagnetic nature.
Diamagnetic materials don’t exhibit any magnetic properties naturally, they only counter an external magnetic field by repelling it.
Practical Examples of Magnetic Materials
6. Iron
Iron is a ductile and malleable metal which is grey in color and can conduct both heat and electricity. Iron and its alloys make strong magnets and are also attracted by other magnets.
Ferromagnetic materials like iron are used in various applications including; transformers, electric motors, magnetic storage, generators, etc.
7. Nickel
Nickel is a ductile and malleable metal with high resistance to corrosion. It is used in making coins and gas turbines.
Nickel obtains its magnetic properties from the free electrons within its outermost shell. Nickel falls under ferromagnetic materials because it can both attract and be attracted by magnetic materials.
8. Erbium
Erbium is a malleable material which is mostly used in making control rods for nuclear reactors.
The magnetic properties of erbium change depending on the temperature. At temperatures above 85 K, erbium is paramagnetic. At temperatures between 20 and 85 K, erbium is antiferromagnetic. It becomes ferromagnetic at temperatures below 20 K.
9. Germanium
Germanium is a hard, brittle metalloid with a crystalline structure like that of diamond. Another unique property of germanium is that it expands on freezing.
Germanium belongs to group IV with diamagnetic properties. However, these magnetic properties can change depending on the temperature levels.
10. Terbium
Terbium is a ductile metal with just a few commercial applications since it is expensive. Terbium exhibits ferromagnetic properties at temperatures up to 221 K. At temperatures above 228 K, terbium exhibits paramagnetic properties.
11. Cobalt
Cobalt is a stable metal in water and air and is mostly used in lithium-ion batteries. It is also used in making hard and soft magnets.
Cobalt is a ferromagnetic material since it is strongly attracted by other magnets due to its three free moving electrons.
12. Neodymium
Neodymium is a hard silvery metal with strong magnetic properties. It is a ferromagnetic material; it is magnetized by other magnets. Neodymium materials make the strongest magnets in the world and can attract 1,000 times weight than their own.
Neodymium magnets are used in applications like headphones, microphones and loudspeakers.
13. Samarium
Samarium is a stable metal at room temperature and occurs naturally in a silvery-white color. Samarium element forms a stronger magnet when combined with cobalt. Samarium is used as a neutron absorber for nuclear reactors and in infrared absorbing applications.
14. Magnetite
Magnetite is one of the most magnetic materials that exist. It is also known as lodestone and occurs naturally in black, grey color. Magnetite is primarily used in the manufacture of steel. Other applications of magnetite include; making ammonia, paints and ceramics, etc.
Conclusion
Magnetism is a naturally occurring phenomenon and most naturally occurring metals have magnetic properties. However, some metals have stronger magnetic properties than others, ferromagnetic materials are stronger magnets.
Generally, apart from ferromagnetic materials, other magnetic elements can only be detected in the laboratory using magnetic detectors. Also, non-metals don’t have any magnetic properties.
