Magnets are an integral part of our everyday life. They come across us in various shapes, colors or sizes and are used for very different purposes: neodymium magnets, electromagnets, as bar/rod and ring magnets or in the well-known horseshoe magnet form - but what do we actually know about them? The word 'magnet' comes from the Greek and means something like 'stone from Magnesia'. This is a stretch of land on the Hellenic peninsula where the ancient Greeks are said to have first encountered an iron-attracting stone (magnetite) over 2000 years ago. The history of magnets is still the focus of the interests of countless natural sciences. In general, the magnet corresponds to a body that magnetically attracts or repels another body. This phenomenon is also known as magnetism and is a fundamental natural phenomenon.
Why is a magnet magnetic?
A magnet creates a magnetic field and it flows through it, as it were. So-called field lines illustrate the magnetic forces. The areas through which most of the magnetic field flows are called poles. The opposite poles are the north and south poles. Without magnetic fields, there would be no magnetic forces, since otherwise the force between the magnet and the magnetizable object would be missing The world also has an earth's magnetic field (e.g. recognizable by a compass). The causes of this earth's magnetic field are probably hidden deep inside the earth, where electrically conductive matter circulates and moves in hot currents. Electrical charges are the keyword here. The law of induction is responsible for the creation of magnetic fields (electromagnets) when electric charges move. On the other hand, certain elementary particles have their own magnetic moments as a result of their spin, i.e. the natural angular momentum of their fundamental particles (permanent magnet).
What types of magnets are there?
- Diamagnetism: Diamagnetic materials have no magnetic properties without an external magnetic field. They develop an induced magnetic field that is opposite to the external magnetic field.
- Paramagnetism: Paramagnetic substances also require an external magnetic field. magnetization then increases more inside than outside, which means that paramagnets are drawn into a magnetic field.
- Ferromagnetism: The best known type of magnetism. The magnetic moments of the ferromagnets tend to align in parallel. For example, ferromagnets either generate a permanent magnetic field themselves or are strongly attracted to an external magnetic field. As classic solid bodies, permanent magnets, electric motors or transformers are the most common applications.
- Antiferromagnetism: The neighboring elementary magnets in antiferromagnetic materials have the same amount, but are oriented in opposite directions. No magnetization can be measured without an external magnetic field. Above a certain temperature limit (Néel temperature), antiferromagnetic substances behave like paramagnets.
- Ferrimagnetism: Ferrimagnetic substances have a crystal structure in which the magnetic moments in the so-called Weißes districts are alternately aligned antiparallel. In contrast to ferromagnetism, the magnetic order of the elementary magnets differs, which means that ferrimagnets are somewhat weaker than ferromagnets.
Magnets and their value for humanity
Since the discovery and research of magnets, their range of uses for humans has been enormous. As components in technology and industry, to simple permanent magnets for the refrigerator. There are many different magnet products to buy that differ in strength or adhesive force.
Magnetic memo walls, self-adhesive magnetic tape, mini magnets, magnetic mats or sphere magnets - no matter in which form magnetic materials are used, they are all united by the magnetic attraction forces.
In the course of time, sophisticated alloys and strong magnet systems were developed through experimental research. The best known include: