This chapter gives a brief account of some of the phenomena on an atomic scale which contribute to the macroscopically observable dielectric and magnetic properties of solids. The discussion of certain topics has been abbreviated or curtailed for two reasons, and a bibliography of more extended accounts is provided at the end of the chapter as a supplement to the limited or descriptive coverage given here.

One reason for compressing dielectric and magnetic phenomena (which are two extremely active fields of solid state research) into a single chapter is that the subjects we shall discuss here have a rather different emphasis than the subject matter of the previous four chapters. Up to this point we have been almost continuously concerned with the consequences of periodicity in real space and in k-space. To be sure, the long range order of a crystalline lattice is significant in any discussion of ferroelectric, ferromagnetic, or antiferromagnetic behavior, but most of the topics in this chapter are less directly involved with the existence of a strictly periodic k-space.

I have also tried to be brief, and thus far from comprehensive, on many of the aspects of dielectric and magnetic behavior in order to hold the total length of this book to a reasonable length for a one semester course (recognizing that there will always have to be selection of topics from within each of the five chapters). Accordingly, several of the topics are dealt with on a purely descriptive basis, relying on the bibliography for further source material.