  Ag/BSCCO and Fe/Ag/BSCCO planar tunnel junctions were constructed in order to
study experimentally the effect of an exchange potential on the spin polarized
current transported through Andreev bound states appearing at the interface
with a superconductor with broken time reversal pairing symmetry. The zero bias
conductance peak (ZBCP) resulting from the Andreev bound states (ABS) is split
into two symmetric peaks shifted at finite energies when the counterlectrode is
normal. Four asymmetric peaks are observed when the ferromagnetic spin
polarized charge reservoir is added, due to the combined effect of a
spin-filtering exchange energy in the barrier, which is a spin dependent
phenomenon, and the spin independent effect of a broken time reversal symmetry
(BTRS). The polarization in the iron layer leads to asymmetry. Due to the shift
of ABS peaks to finite energies, the conductance at zero energy behaves as
predicted by recent theoretical developments for pure d-wave junctions without
Andreev reflections.
