Remark: The author of this website does not take any liability related to damages, claims or disadvantages, which are originated by the use of the information of this theory chapter. By using one of the buttons below this statement will be accepted. In this case the user will be liable completely by its own for all resulting legal and commercial consequences. This collection of articles will not be able to provide a complete understanding of the field of permanent magnetism and is an attempt only  to provide a basic introduction.


Basic Parameters of Permanent Magnetism

This article offers an explanation of the most important parameters of permanent magnetism like magnetization, magnetic moment, magnetic polarization, susceptibility, permeability and others. Here we also depict the famous Maxwell equations as well as the difference between the so called H- and B- fields. Additionally the reader will be introduced into basic magnetic phenomena like ferromagnetism, paramagnetism, diamagnetism etc.


Hysteresis and Demagnetization Curve

Here we will have a look on magnetic hysteresis. Whereas the first quadrant of hysteresis describes the magnetizing behavior of respective materials at external fields, the second quadrant is very important for the operation of already magnetized magnets. The second quadrant is often called demagnetization curve. The most important parameters for the demagnetization curve like remanence induction, coercivity or maximum energy product are explained here. Additional terms like demagnetization factor, internal field and others will be treated also.


Stability of Permanent Magnets

The stability of permanent magnets, i.e. the question under which conditions fields or forces of permanent magnets are constant, is important from technical as well as from general viewpoints. Changes of magnetic characteristics are basically classified into reversible and irreversible effects. Both sorts can be originated by changes of temperature as well as by external magnetic fields. Whether reversible or irreversible processes take place is especially governed by the so called load line, which describes the status of internal and external fields in the material. The explanation of the most relevant aspects as well as an overview over the basic contexts and mechanisms will be shown here.


Magnetic Materials

Here the most important commercially available permanent magnetic materials will be described. In detail these are ceramic Ferrites, NdFeB, Samarium Cobalt and Alnico alloys. They still govern the world wide market for permanent magnets. Beside a general explanation of their specific characteristics we will also provide some numerical examples for their basic parameters.


Computation of Permanent Magnetic Fields

This chapter will deal with the computation of magnetic fields that are originated by permanent magnets. Beside a general explanation of the basic differential equations, a short introduction to numerical methods like the FEM method will be given. The analytical treatment of  permanent magnets will then be explained  in detail by showing the related formulas. Such analyses can be done by use of the magnetic vector potential as well as by using the magnetic scalar potential. A short introduction to some of the basic subjects of mathematical vector analysis completes this chapter.


Atomic Origins of Magnetism

Here follows an explanation of the quantum theoretical origins of the electrons magnetic moment, which results from spin and angular momentum. In addition we elucidate the coupling of the moments of the single electrons to form the total magnetic moment of the atom. Following this the mutual interactions of the atoms are discussed, which lead to the phenomena of  ferromagnetism, paramagnetism and diamagnetism under the action of  fields and temperature. Related equations for the magnetic moment, especially for the ferromagnetic case, are sketched in their quantum theoretical derivation and the respective effects are explained in detail.

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