Theory of Heavy Fermion Systems

Abstract

Publisher Summary The chapter presents a study on theory of heavy fermion systems. In the heavy fermion systems it seems that some of the features of the single Kondo impurity problem appear in an enhanced form simply, because there is at least one magnetic ion per unit cell. Therefore, the heavy fermion systems have sometimes been referred to as “lattices of Kondo ions” or “Kondo lattice systems.” The chapter presents a discussion on quasiparticle-phonon interactions and presents a demonstration that elastic properties of heavy fermion systems are almost as interesting as the electronic ones. Superconducting heavy fermion systems have attracted great interest, because they are considered as possible candidates for unconventional pairing. An outstanding experimental finding is the power-law behavior of the low temperature specific heat, thermal conductivity, ultrasonic attenuation, and nuclear magnetic resonance (NMR) relaxation rate in those systems. The chapter also presents a figure based on the scenario within which the heavy fermion systems should be viewed. It shows the different degrees of electron correlations in solids. The heavy fermion systems are the ones, which come closest to the localization limit, in which electron correlations exclude any charge fluctuations within the f shell.