  We derive perturbation analytic expressions for the Casimir free energy and
entropy between two dissimilar ferromagnetic plates which are applicale at
arbitrarily low temperature. The dielectric properties of metals are described
using either the nondissipative plasma model or the Drude model taking into
account the dissipation of free charge carriers. Both cases of constant and
frequency-dependent magnetic permeability are considered. It is shown that for
ferromagnetic metals described by the plasma model the Casimir entropy goes to
zero when the temperature vanishes, i.e., the Nernst heat theorem is satisfied.
For ferromagnetic metals with perfect crystal lattices described by the Drude
model the Casimir entropy goes to a nonzero constant depending on the
parameters of a system with vanishing temperature, i.e., the Nernst heat
theorem is violated. This constant can be positive which is quite different
from the earlier investigated case of two nonmagnetic metals.
