Magnetic Materials: Fundamentals and Applications
Author: Nicola A. Spaldin
Edition: Second revised
Publisher: Cambridge University Press
Many authors have attempted to write undergraduate textbooks on the fundamental magnetic properties of materials; only a handful have succeeded. All too often, the student ends up confused by the myriad definitions of the plethora of fields that invariably appear in various contexts, without any clear, qualitative description of how they all fit together. The apparent mysticism of the behaviour of magnetic fields in materials, combined with the apparently different approaches to the subject taken by physicists and engineers and the frequent deviations from SI units, merely add to the confusion.
Nicola Spaldin's text is an enthusiastic attempt to address a difficult subject from both an engineering and a physics perspective. Unfortunately, however, the text fails to make the transition to the written page from what is almost certainly an entertaining lecture course, and it suffers from many of the failings of its predecessors. Its promise to provide an improved understanding of the basic magnetic phenomena flounders in the early chapters, with only a passing reference to the Faraday-Lenz law and a belated introduction of the magnetic flux density, B, which is the cornerstone of the understanding of forces in most engineering devices. The differentiation of B and H (which are merely different measures of the same field in free space) by material response is misleading.
The introductory chapters are bogged down with formal, equation-based definitions without sufficient qualitative explanation. For example, less than a page is used to describe magnetic hysteresis, which forms the basis of the application of all permanent magnets.
The text then leaps into the quantum mechanics of magnetic materials, again without making the qualitative connection between the fundamental materials' properties, including electron spin, which is essential for the non-physicist. The starting point of such an approach is naturally the Pauli exclusion principle to explain why unpaired spins exist at all; sadly this is lost in the detail of the wave function and the Hamiltonian.
However, the text certainly improves after the description of the basic properties, with well-organised and informative descriptions of superconductors, ferrimagnetism, ferromagnetism and the topical magnetoresistive materials. Spaldin also picks her way successfully through some potentially difficult discussion of anisotropy and demagnetising effects. The text finishes with a qualitative discussion of magnetic devices and materials, appropriate for undergraduates of all the physical sciences.
The book is a reasonable introduction to aspects of the properties of a relatively wide range of magnetic materials, despite an unconvincing attempt to address the fundamental aspects of magnetic phenomena. It suffers from too much detail and insufficient qualitative explanation in parts, although the later chapters recover its potential as a useful aid to teaching and learning.
Who is it for? First- and second-year undergraduate students taking courses in physics, electrical engineering and materials science.
Presentation: The text is written in a fairly clear format and is illustrated schematically throughout. There is a reasonable balance between the fundamental physical concepts and practical applications, although the link between them is not that clear.
Would you recommend it? Probably yes, to first-year undergraduate physical science students, but only as additional reading (ie, not as a core text).
David A. Cardwell is professor of superconducting engineering, department of engineering, University of Cambridge.