Magnetic phenomena

In the broad range of ceramic materials that are used for electrical and electronic apphcations, each category of material exhibits unique property characteristics which directiy reflect composition, processing, and microstmcture. Detailed treatment is given primarily to those property characteristics relating to insulation behavior and electrical conduction processes. Further details concerning the more specialized electrical behavior in ceramic materials, eg, polarization, dielectric, ferroelectric, piezoelectric, electrooptic, and magnetic phenomena, are covered in References 1—9. 

There is usually no problem in converting between 4D and Gaussian quantities until we have to consider electrical and magnetic phenomena. In the Gaussian system we take the proportionality constant in Coulomb s law to be unity (a number),... 

Faraday returned to chemisti y, but after 1830, his investigations again concentrated on electric and magnetic phenomena. He had become convinced that the reverse action to the phenomenon discovered by Oersted was also possible, that a magnetic... 

H and 13C nuclei are not unique in their ability to exhibit the NMR phenomenon. All nuclei with an odd number of protons H, 2H, l4N, 19F, 31P, for example) and all nuclei with an odd number of neutrons (13C, for example) show magnetic properties. Only nuclei with even numbers of both protons and neutrons (l2C, 160) do not give rise to magnetic phenomena (Table 13.1). 

In conclusion we note that the method of alternant molecular orbitals leads to a correct behavior of the energy curve for separated atoms, which is of essential importance in considering correlation effects (see Section II.D(4c)) and in studying magnetic phenomena. 

The above statements apply to an assembly of independent spins. Deviation from proportionality, if any is observed, suggests the presence of cooperative magnetic phenomena, i.e. ferro-, antiferro-, ferri-, meta-, micto-magnetism, and so on. The magnetic susceptibility at above the spinordering temperature (Tq) can be usually fitted by the Curie-Weiss expression (18) with the Weiss temperature 0 > 0 for the sample with dominant... 

Despite the intrinsic complexity of magnetic phenomena, there is general agreement... 

The basic principles of magnetism are described in essentially every solid-state physics text. A classic reference for this genre is C. Kittel, Introduction to Solid State Physics, Wiley, New York, 1976. Several books that focus more specifically on magnetic phenomena are M. Getzlaff, Fundamentals of Magnetism, Springer,... 

Booy M. Swaddle, T.W. (1978) Hydrothermal preparation of magnetite from iron chelates. Can. J. Chem. 56 402-403 Boquet, S. Pollard, R.J. Cashion, J.D. (1990) Dynamic magnetic phenomena in fine particle goethite. Phys. Rev. B46 11657-11664... 

B. A permanent magnetic moment and, possibly, collective magnetic phenomena. 

As far as magnetic phenomena are concerned, if the system is all in the lower subband (i.e. localized) then the treatment for locahzed spins holds, and exchange forces between them may provoke eventually ferro- and anti-ferromagnetism. If the system is itinerant in the unsphtted band then treatments of magnetism in narrow bands such as Stoner s are valid. Hubbard derives also a condition for collective magnetism which is similar to the Stoner s one ... 

In UPts, a compound for which spin-fluctuations are known to exist, superconduction has recently been reported There is an apparent contradiction with the classical Bar-deen-Cooper model for superconductivity, in which superconduction is hindered by the onset of ordered magnetic phenomena, and is usually not found in very narrow bands. UBei3 which has a y of 1000 mg/mol K, exhibits similar behaviour. 

Detonation (and Explosion), Ionization, Electrical, Magnetic, and Electromagnetic Phenomena Accompanying It. See under Detonation (and Explosion), Electrical, Electromagnetic, and Magnetic Phenomena Accompanying It... 

English physicist who discovered electromagnetic induction and many other vital electrical and magnetic phenomena. 

We end this book with an overview of a topic that has immense promise but is still in the laboratory stage of development, namely, high temperature superconductivity.22 24 Since superconductivity is intimately related to magnetic phenomena in solids, a brief consideration of magnetochemistry25 is prerequisite. 

In this section, we first discuss predictions of ab initio computations in comparison to photoemission and x-ray magnetic-circular dichroism data, discussed already in the previous sections. Theoretical models employing parameterized Hamiltonians are presented next emphasizing their successes and shortcomings in the description of magnetic phenomena. 

As might be anticipated from the Maxwellian symmetry of electric and magnetic phenomena, a completely parallel magnetic work form dwmSLg arises from magnetic polarization in... 

Dorfman, Y. G. On the nature of some unusual magnetic phenomena found in certain organic materials. Dokl. Akad. Nauk. 142, 815 (1962) [7,121 (1962)]. 

With liquid helium readily available in the laboratory, research in the temperature range 3 to 0.8 K has become commonplace. By using the isotope of helium -He. it is possible lo attain temperatures down lo about 0.3 K since the isotope has a lower boiling point than JHe. This is about the lowest temperature practically attainable by boiling liquids at reduced pressure. To reach lower temperatures, it is necessary to use magnetic phenomena. 

The combination of the cluster model approach and modem powerful quantum chemistry techniques can provide useful information about the electronic structure of local phenomena in metal oxides. The theoretical description of the electronic states involved in local optical transitions and magnetic phenomena, for example, in these oxides needs very accurate computational schemes, because of the generally very large differential electron correlation effects. Recently, two very promising methods have become available, that allow to study optical and magnetic phenomena with a high degree of precision. The first one, the Differ-... 

This chapter is oriented toward the nonspecialist. It tries to illustrate some standard experimental techniques and describe selected theoretical models used to interpret the observed magnetic data, along with their inherent limitations. Given the sheer complexity and diversity of magnetic phenomena of inorganic compounds, it is beyond the scope of this chapter to provide a complete overview. Instead, this chapter aims to highlight selected basic methods and models and, where reasonable, hands-on rules. 

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