Foreword

There are many good books describing the foundations and basics of solid state physics, such as Introduction to Solid State Physics by C. Kittel (2004) or, on a somewhat higher level, Solid State Physics by N. W. Ashcroft and N. D. Mermin (1976). However there is a definite lack of books of a more advanced level which would describe the modern problems of solid state physics (including some theoretical methods) on a level accessible for an average graduate student or a young research worker, including experimentalists.

Usually there exists a rather wide gap between such books written for theoreticians and those for a wider audience. As a result many notions which are widely used nowadays andwhich determine ‘the face’ of modern solid state physics remain ‘hidden’ and are not even mentioned in the available literature for non-specialists.

The aim of the present book is to try to fill this gap by describing the basic notions of present-day condensed matter physics in a way understandable for an average physicist who is going to specialize in both experimental and theoretical solid state physics, and more generally for everyone who is going to be introduced to the exciting world of modern condensed matter physics – a subject very much alive and constantly producing new surprises.

In writing this book I tried to follow a unifying concept throughout. This concept, which is explained in more detail below, may be formulated as the connection between an order in a system and elementary excitations in it.