  We present a theoretical study of the effect of spin-filtering on the
Josephson and dissipative quasiparticle currents in a superconducting tunnel
junction. By combining the quasiclassical Green's functions and the tunneling
Hamiltonian method we describe the transport properties of a generic junction
consisting of two superconducting leads with an effective exchange field h
separated by a spin-filter insulating barrier. We show that besides the
tunneling of Cooper pairs with total spin-projection Sz = 0 there is another
contribution to the Josephson current due to equal-spin Cooper pairs. The
latter is finite and not affected by the spin-filter effect provided that the
fields h and the magnetization of the barrier are non-collinear . We also
determine the quasiparticle current for a symmetric junction and show that the
differential conductance may exhibit peaks at different values of the voltage
depending on the polarization of the spin-filter, and the relative angle
between the exchange fields and the magnetization of the barrier. Our findings
provide a plausible explanation for existing experiments on Josephson junctions
with magnetic barriers, predict new effects and show how spin-polarized
supercurrents in hybrid structures can be created.
