ABSTRACT
Cobalt oxides are known to exhibit peculiar physical/chemical
properties, aswell as being suitable candidates forwide applications
such as electrode materials, thermoelectric materials, solid oxide
fuel cells, and so forth. Such properties are closely related to
versatility of the cobalt cations to adopt different valences and
spin states in the narrow energy range, which associate with the
charge and spin configuration on 3d orbitals, respectively. In this chapter, the charge, spin, and orbital for the 3d electron system are introduced, and then their role in the transport properties under
external perturbations is formulated.