Properties of Magnetic Materials

Just as materials have a response when placed in an electric field, they can have a response when placed in a magnetic field. We will see in this section that many of the concepts of permanent dipoles and dipole alignment in response to an applied field that were described in the context of electrical fields apply to magnetic fields as well. There are a few differences, however, and we will also see that there are fewer materials with specialized magnetic properties than there were with specialized electrical and electronic properties. The magnetic properties of materials are nonetheless important, and they are applied in a number of technologically important areas. 

Recall from Eq. (6.2) that the induction and field are related as follows  

The quantity (1 + /) is called the relative magnetic permeability (also dimensionless), which is also a material property. 

A coil of wire 0.20 m long and having 200 tnms carries a current of 10 A. 

Person 1 Calculate the magnetic field strength in vacuum. 

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Study of Magnetic Properties of Materials Using the Mossbauer Effect... 

There are several fundamental experiments on the magnetic properties of materials that become possible as a result of the low-temperature environment of cryogenics. The first of these was discovered by deHaas and Van Alphen in 1930. They found that at low temperatures, the susceptibility of bismuth single crystals rose and fell periodically as the magnetic field was increased. Later work shows that the periodicity occurs in all metals at low temperatures and is the result of quantization of electron motion perpendicularly to the applied field. This effect was used to determine the Fermi surface of metals. 

At the time, it is difficult to imagine industrial and household devices that do not use magnetic sensors, magnetic devices or elements of magnetic memory. Because of this, it is quite clear that interest in magnetic properties of materials and, in particular, granular metals is actual and permanent one. 

The excellent permanent magnetic properties of materials based on Nd2Fei4B were discovered in 1983. Very soon afterwards strong, small permanent magnets were available commercially with a Curie temperature of 850 K and a very high energy product (BH)max- This quantity for Nd2Fei4B is... 

In the electrochemical investigations of HTSC it is of great importance to control the resistive and magnetic properties of materials during synthesis as well as before and after the electrochemical experiments. Only independent measurements of both... 

Often the electronic spin mainly plays the indirect role through the Pauli principle, but in some cases it is directly the source of physical processes. Magnetism is an obvious example, and the combination of spin- and orbital moments determines the magnetic properties of materials. The theory must therefore be able to treat spin-polarization and SO-coupling simultaneously. This is therefore the third subject dealt with here. Magnetoelastic and magnetooptic effects are related to this and are discussed in Section 5. 

Winkler, G. (1971). Crystallography, chemistry and technology of ferrites. In Magnetic Properties of Materials. Ed. J. Smit. McGraw-Hill, London, pp. 20-63. 

Smit, J. (1971). Magnetic Properties of Materials, McGraw-Hill, New York. 

S4.4 Formulae and units used to describe the magnetic properties of materials... 

FORMULAE AND UNITS USED TO DESCRIBE THE MAGNETIC PROPERTIES OF MATERIALS 551... 

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