ABSTRACT
SCESs comprise a large class of materials, including Kondo impurity systems, Kondo lattice
systems, high T
superconductors, transition metal oxides, strontium ruthenates, manganite
compounds, organic metals, mesoscopic systems, and quantum dots. Electrons are considered to
be “strongly correlated” if the energy associated with their mutual Coulomb repulsion is larger than
their kinetic energy. In this case the motion of one electron is not independent of that of all others
and the electrons are correlated. For a theoretical description of such systems, many-body techniques
need to be employed. In this review I shall focus on the first two classes of materials, Kondo impurity
systems and Kondo lattice systems, where two electronic subsystems, itinerant-and localized-type,
strongly interact with each other. The itinerant subsystem comprises charge carriers derived from s, p,
and/or d orbitals while the localized subsystem consists of charge carriers from f (and in a few cases
from d) orbitals. The strong interaction between charge carriers of these two subsystems leads to
a wealth of extraordinary phenomena. Most important in the context of thermoelectric applications is
the appearance of giant thermopowers in some of these systems. This phenomenon shall be treated in
detail below. The discussion of other properties influencing the efficiency of a material in a
thermoelectric device is described in Section 15.4.
