  In tunneling spectroscopy studies of ferromagnet/superconductor (F/S)
junctions, the effects of spin polarization, Fermi wavevector mismatch (FWM)
between the F and S regions, and interfacial resistance play a crucial role. We
study the low bias conductance spectrum of these junctions, governed by Andreev
reflection at the F/S interface. We consider both d- and s-wave superconductors
as well as mixed states of the $d+is$ form. We present results for a range of
values of the relevant parameters and find that a rich variety of features
appears, depending on pairing state and other conditions. We show that in the
presence of FWM, spin polarization can enhance Andreev reflection and give rise
to a zero bias conductance peak for an s-wave superconductor.
