  Explicit energy-transport equations for the spinorial carrier transport in
ferromagnetic semiconductors are calculated from a general spin
energy-transport system that was derived by Ben Abdallah and El Hajj from a
spinorial Boltzmann equation. The novelty of our approach are the simplifying
assumptions leading to explicit models which extend both spin drift-diffusion
and semiclassical energy-transport equations. The explicit models allow us to
examine the interplay between the spin and charge degrees of freedom. In
particular, the monotonicity of the entropy (or free energy) and gradient
estimates are shown for these models and the existence of weak solutions to a
time-discrete version of one of the models is proved, using novel truncation
arguments. Numerical experiments in one-dimensional multilayer structures using
a finite-volume discretization illustrate the effect of the temperature and the
polarization parameter.
