Magnetic properties of matter

If you place an object in a magnetic field , then its "behavior" and the type of internal structural changes will depend on the material from which the object is made. All known substances can be divided into five main groups: paramagnetics, ferromagnets and antiferromagnets, ferrimagnets and diamagnets. According to this classification, the magnetic properties of a substance are distinguished. To understand what is hidden behind these terms, consider each group in more detail.

Substances exhibiting the properties of paramagnetism are characterized by a magnetic permeability with a positive sign, regardless of the value of the strength of the external magnetic field in which the object is. The most famous representatives of this group are nitric oxide and gaseous oxygen, metals of alkaline earth and alkaline groups, and also ferrous salts.

The high magnetic susceptibility of the positive sign (reaching 1 million) is inherent in ferromagnets. Being dependent on the intensity of the external field and temperature, the susceptibility varies widely. It is important to note that since the moments of elementary particles of different sublattices in the structure are equal, the total value of the moment is zero.

As for the name, and for some properties, they are close to ferrimagnetic substances. They are united by a high dependence of the susceptibility on heating and the value of the field strength, but there are also differences. The magnetic moments of the atoms placed in the sublattices are not equal to each other, therefore, unlike the previous group, the total moment is different from zero. The matter is inherent spontaneous magnetization. The coupling of the sublattices is antiparallel. The most famous are ferrites. The magnetic properties of the substances in this group are high, so they are often used in engineering.

Of particular interest is the group of antiferromagnets. When such substances are cooled below a certain temperature boundary, the atoms and their ions located in the crystal lattice structure naturally change their magnetic moments, acquiring an antiparallel orientation. A completely different process takes place when the substance is heated: it records the magnetic properties characteristic of a group of paramagnets. Examples include carbonates, oxides, etc.

And, finally, diamagnetics. The magnetic properties of the substance of this group are in no way dependent on the field strength, and the value of the magnetic susceptibility is negative. If the substance has a covalent bond, then it is a "pure" diamagnet. Representatives - gold, copper, inert gases , etc.

Magnetic properties of the substance are widely used in modern technology. For example, windings of windings of transformers are wound on soft magnetic materials. High magnetic permeability and magnetization to the saturation state, even in a low-intensity field, mean a narrow hysteresis loop on the graph, as well as insignificant losses due to magnetization reversal, which is in demand in electrical engineering. If the magnetic properties of a substance correspond to a soft magnetic material, then a significant flux is characteristic of the product, limited only by saturation. In practice, this means the possibility to reduce the dimensions of the magnetic circuit, thereby reducing the mass of the device. However, in advantages there is also a disadvantage - the alternating field generates eddy currents in such material causing heating, so the compromise solution is the lamination of the conductor.

Another type of material is magnetically hard, coercive force for which is not less than 4000 amperes per meter. This means that magnetic reversal requires high magnetic fields, after which the material retains its magnetic properties, becoming a permanent magnet.