Abstract
An introduction to the theory of heavy-fermion systems is given. Emphasis is put on the physical arguments which accompany the various theoretical models rather than presenting the latter in all details. After an introduction to the subject, the ground state and the description of the heavy quasiparticles are discussed. The origin of the low-lying excitations is considered in detail. This is followed by a discussion of the quasiparticle interactions. The interaction of quasiparticles with phonons is studied rather extensively. Of particular interest is the hydrodynamic regime for which a theory of the density fluctuations is presented. Finally theoretical models for superconductivity in heavy-fermion systems are discussed. Special attention is paid to the pairing interactions and the nature of the pair state.