The Kondo Problem to Heavy Fermions

The behaviour of magnetic impurities in metals has posed problems to challenge the condensed matter theorist over the past thirty years. This book deals with the concepts and techniques which have been developed to meet this challenge, and with their application to the interpretation of experiments. After an introduction to the basic theoretical models, Kondo's explanation of the resistance minimum is described, which was the first of the major puzzles to be solved. As Kondo's perturbational calculations break down at low temperatures a non-perturbational approach is needed to predict the low temperature behaviour of the models, the so-called Kondo problem. The author surveys in some detail the many-body techniques, scaling, renormalization group, Fermi liquid and Bethe ansatz, which lead to a solution of this problem for most of the theoretical models. The book also deals with special techniques for N-fold degenerate models for rare earth impurities (including mean field and 1/N expansions). The theoretical framework having been established, a comparison is made between theoretical predictions and the experimental results on particular systems in the penultimate chapter. With the success of the many-body techniques developed to deal with impurity problems the new challenge is the extension of these strong correlation techniques to models with periodicity in order to understand the behaviour of heavy fermion and high T[subscript c] superconducting compounds. The work which has provided insights into heavy fermion behaviour is reviewed in the last chapter, together with the questions that need to be answered in future work. This book will be of interest to condensed matter physicists, particularly those interested in strong correlation problems. The detailed discussions of advanced many-body techniques should make it of interest and useful to theoretical physicists in general.