  A simple two-band model is used to describe the magnitude and temperature
dependence of the magnetic susceptibility, Hall coefficient and Seebeck data
from undoped and Co doped BaFe2As2. Overlapping, rigid parabolic electron and
hole bands are considered as a model of the electronic structure of the
FeAs-based semimetals. The model has only three parameters: the electron and
hole effective masses and the position of the valence band maximum with respect
to the conduction band minimum. The model is able to reproduce in a
semiquantitative fashion the magnitude and temperature dependence of many of
the normal state magnetic and transport data from the FeAs-type materials,
including the ubiquitous increase in the magnetic susceptibility with
increasing temperature.
