  We study transport phenomena through a ballistic
ferromagnet-superconductor-ferromagnet (F/S/F) junction, comparing the case in
which the ferromagnetic order in the two F layers is of the standard Stoner
type with the case where it is driven by a spin mass mismatch (SMM). It is
shown that the two mechanisms lead to a different behavior in the charge and
the spin conductances, especially when compared to the corresponding
non-superconducting ferromagnet-normal-ferromagnet (F/N/F) junctions. In
particular, when the injected current is perpendicular to the barrier, for high
barrier transparency and large magnetization of the F layers, the large mass
mismatch gives rise to an enhancement of both low-bias charge and spin
conductances of the F/S/F junction, which is not observed in the equal-mass
case. When all the allowed injection directions are considered, the low bias
enhancement of the charge conductance for SMM leads still holds for high
barrier transparency and large magnetization of the F layers. However, in the
case of non-transparent interfaces, spin transport with SMM ferromagnets
exhibits an opposite sign response with respect to the Stoner case at high
biases for all magnetization values, also manifesting a significant
amplification induced by superconductivity at the gap edge. The above mentioned
differences can be exploited to probe the nature of the electronic mechanism
underlying the establishment of the ferromagnetic order in a given material.
