ABSTRACT
All beginnings are difficult, but we must somehow start, so let us do it as simply as possible. Pictures are worth many words, thus, some oversimplified sketches are used to illustrate what a spin glass is and how we create the all-important randomness. In addition to the disorder we must have magnetic interactions, and these are also treated in a pictorial way. The other important ingredients of a spin glass, anisotropy and frustration, are introduced via easy examples. After formulating a working definition of a spin glass we take a first look at the freezing process. The spin glass does indeed constitute a new state of magnetism, distinctly different from the long-range ordered ferro-and antiferromagnetic phases. Yet similar to these magnets, the spin glass also has a co-operative or collective nature in the frozen state. And this is what we must try to understand and put into a clear physical presentation with the aid of ‘solvable’ theoretical models. In order to satisfy the biographic aspects we give a very brief account of the historical development of the spin-glass problem and how the name was coined in 1970. With such an outline of the goals of Chapter 1, let us plunge into the spin glasses.
